| Month | Data | Change | Unit |
|---|---|---|---|
| January, 1973 | 57.8 | 0 | Percent |
| February, 1973 | 60.7 | + 2.9 | Percent |
| March, 1973 | 58.4 | -2.3 | Percent |
| April, 1973 | 53.4 | -5 | Percent |
| May, 1973 | 47.3 | -6.1 | Percent |
| June, 1973 | 50.3 | + 3 | Percent |
| July, 1973 | 50 | -0.3 | Percent |
| August, 1973 | 54.5 | + 4.5 | Percent |
| September, 1973 | 56.9 | + 2.4 | Percent |
| October, 1973 | 49.8 | -7.1 | Percent |
| November, 1973 | 55.8 | + 6 | Percent |
| December, 1973 | 47.6 | -8.2 | Percent |
| January, 1974 | 45 | -2.6 | Percent |
| February, 1974 | 50.9 | + 5.9 | Percent |
| March, 1974 | 49.8 | -1.1 | Percent |
| April, 1974 | 41 | -8.8 | Percent |
| May, 1974 | 34.6 | -6.4 | Percent |
| June, 1974 | 37.5 | + 2.9 | Percent |
| July, 1974 | 52.3 | + 14.8 | Percent |
| August, 1974 | 58.9 | + 6.6 | Percent |
| September, 1974 | 50.9 | -8 | Percent |
| October, 1974 | 47.7 | -3.2 | Percent |
| November, 1974 | 48.7 | + 1 | Percent |
| December, 1974 | 56 | + 7.3 | Percent |
| January, 1975 | 57.3 | + 1.3 | Percent |
| February, 1975 | 54.9 | -2.4 | Percent |
| March, 1975 | 58 | + 3.1 | Percent |
| April, 1975 | 52.4 | -5.6 | Percent |
| May, 1975 | 52.4 | 0 | Percent |
| June, 1975 | 50.1 | -2.3 | Percent |
| July, 1975 | 58.5 | + 8.4 | Percent |
| August, 1975 | 60.5 | + 2 | Percent |
| September, 1975 | 56.6 | -3.9 | Percent |
| October, 1975 | 55.6 | -1 | Percent |
| November, 1975 | 54.4 | -1.2 | Percent |
| December, 1975 | 60.2 | + 5.8 | Percent |
| January, 1976 | 58.1 | -2.1 | Percent |
| February, 1976 | 55.4 | -2.7 | Percent |
| March, 1976 | 50.5 | -4.9 | Percent |
| April, 1976 | 40 | -10.5 | Percent |
| May, 1976 | 41 | + 1 | Percent |
| June, 1976 | 54.9 | + 13.9 | Percent |
| July, 1976 | 59.7 | + 4.8 | Percent |
| August, 1976 | 62 | + 2.3 | Percent |
| September, 1976 | 58.7 | -3.3 | Percent |
| October, 1976 | 57 | -1.7 | Percent |
| November, 1976 | 54.8 | -2.2 | Percent |
| December, 1976 | 64.8 | + 10 | Percent |
| January, 1977 | 66.8 | + 2 | Percent |
| February, 1977 | 65.5 | -1.3 | Percent |
| March, 1977 | 62.4 | -3.1 | Percent |
| April, 1977 | 62 | -0.4 | Percent |
| May, 1977 | 62.1 | + 0.1 | Percent |
| June, 1977 | 67.1 | + 5 | Percent |
| July, 1977 | 65.8 | -1.3 | Percent |
| August, 1977 | 66.2 | + 0.40000000000001 | Percent |
| September, 1977 | 59 | -7.2 | Percent |
| October, 1977 | 55.3 | -3.7 | Percent |
| November, 1977 | 58.5 | + 3.2 | Percent |
| December, 1977 | 69 | + 10.5 | Percent |
| January, 1978 | 75 | + 6 | Percent |
| February, 1978 | 70.2 | -4.8 | Percent |
| March, 1978 | 63.7 | -6.5 | Percent |
| April, 1978 | 49.7 | -14 | Percent |
| May, 1978 | 55.8 | + 6.1 | Percent |
| June, 1978 | 62.6 | + 6.8 | Percent |
| July, 1978 | 68.3 | + 5.7 | Percent |
| August, 1978 | 69.9 | + 1.6 | Percent |
| September, 1978 | 61.7 | -8.2 | Percent |
| October, 1978 | 60.9 | -0.8 | Percent |
| November, 1978 | 69.2 | + 8.3 | Percent |
| December, 1978 | 67.2 | -2 | Percent |
| January, 1979 | 73.8 | + 6.6 | Percent |
| February, 1979 | 76.2 | + 2.4 | Percent |
| March, 1979 | 65.7 | -10.5 | Percent |
| April, 1979 | 51.6 | -14.1 | Percent |
| May, 1979 | 40.6 | -11 | Percent |
| June, 1979 | 44.9 | + 4.3 | Percent |
| July, 1979 | 56.3 | + 11.4 | Percent |
| August, 1979 | 65.4 | + 9.1 | Percent |
| September, 1979 | 61 | -4.4 | Percent |
| October, 1979 | 56.5 | -4.5 | Percent |
| November, 1979 | 53.9 | -2.6 | Percent |
| December, 1979 | 55.6 | + 1.7 | Percent |
| January, 1980 | 53.4 | -2.2 | Percent |
| February, 1980 | 55.7 | + 2.3 | Percent |
| March, 1980 | 54.1 | -1.6 | Percent |
| April, 1980 | 52.5 | -1.6 | Percent |
| May, 1980 | 49.7 | -2.8 | Percent |
| June, 1980 | 51.2 | + 1.5 | Percent |
| July, 1980 | 55.5 | + 4.3 | Percent |
| August, 1980 | 63.1 | + 7.6 | Percent |
| September, 1980 | 63.2 | + 0.1 | Percent |
| October, 1980 | 63.5 | + 0.3 | Percent |
| November, 1980 | 56.3 | -7.2 | Percent |
| December, 1980 | 57.4 | + 1.1 | Percent |
| January, 1981 | 61.7 | + 4.3 | Percent |
| February, 1981 | 62 | + 0.3 | Percent |
| March, 1981 | 57.1 | -4.9 | Percent |
| April, 1981 | 55.4 | -1.7 | Percent |
| May, 1981 | 50.4 | -5 | Percent |
| June, 1981 | 54.7 | + 4.3 | Percent |
| July, 1981 | 57.7 | + 3 | Percent |
| August, 1981 | 67.4 | + 9.7 | Percent |
| September, 1981 | 61.7 | -5.7 | Percent |
| October, 1981 | 50.3 | -11.4 | Percent |
| November, 1981 | 57.6 | + 7.3 | Percent |
| December, 1981 | 62.3 | + 4.7 | Percent |
| January, 1982 | 61.6 | -0.7 | Percent |
| February, 1982 | 53.6 | -8 | Percent |
| March, 1982 | 54.6 | + 1 | Percent |
| April, 1982 | 54.1 | -0.5 | Percent |
| May, 1982 | 51.9 | -2.2 | Percent |
| June, 1982 | 59.5 | + 7.6 | Percent |
| July, 1982 | 61.1 | + 1.6 | Percent |
| August, 1982 | 59.9 | -1.2 | Percent |
| September, 1982 | 60.6 | + 0.7 | Percent |
| October, 1982 | 53.7 | -6.9 | Percent |
| November, 1982 | 53.8 | + 0.099999999999994 | Percent |
| December, 1982 | 54.6 | + 0.8 | Percent |
| January, 1983 | 56.6 | + 2 | Percent |
| February, 1983 | 55.4 | -1.2 | Percent |
| March, 1983 | 53.9 | -1.5 | Percent |
| April, 1983 | 52.1 | -1.8 | Percent |
| May, 1983 | 49.5 | -2.6 | Percent |
| June, 1983 | 54.4 | + 4.9 | Percent |
| July, 1983 | 56.2 | + 1.8 | Percent |
| August, 1983 | 57.3 | + 1.1 | Percent |
| September, 1983 | 55.8 | -1.5 | Percent |
| October, 1983 | 55.1 | -0.7 | Percent |
| November, 1983 | 55.3 | + 0.2 | Percent |
| December, 1983 | 56.5 | + 1.2 | Percent |
| January, 1984 | 62.5 | + 6 | Percent |
| February, 1984 | 64.8 | + 2.3 | Percent |
| March, 1984 | 57.4 | -7.4 | Percent |
| April, 1984 | 51.7 | -5.7 | Percent |
| May, 1984 | 53.4 | + 1.7 | Percent |
| June, 1984 | 53.1 | -0.3 | Percent |
| July, 1984 | 57.4 | + 4.3 | Percent |
| August, 1984 | 58.8 | + 1.4 | Percent |
| September, 1984 | 60 | + 1.2 | Percent |
| October, 1984 | 48.6 | -11.4 | Percent |
| November, 1984 | 49 | + 0.4 | Percent |
| December, 1984 | 59.6 | + 10.6 | Percent |
| January, 1985 | 68.8 | + 9.2 | Percent |
| February, 1985 | 63.9 | -4.9 | Percent |
| March, 1985 | 57.2 | -6.7 | Percent |
| April, 1985 | 50.5 | -6.7 | Percent |
| May, 1985 | 52.9 | + 2.4 | Percent |
| June, 1985 | 56.9 | + 4 | Percent |
| July, 1985 | 61.9 | + 5 | Percent |
| August, 1985 | 59.6 | -2.3 | Percent |
| September, 1985 | 61.1 | + 1.5 | Percent |
| October, 1985 | 53.4 | -7.7 | Percent |
| November, 1985 | 52.8 | -0.6 | Percent |
| December, 1985 | 57.2 | + 4.4 | Percent |
| January, 1986 | 60.4 | + 3.2 | Percent |
| February, 1986 | 60.4 | 0 | Percent |
| March, 1986 | 51.3 | -9.1 | Percent |
| April, 1986 | 51.8 | + 0.5 | Percent |
| May, 1986 | 51.7 | -0.099999999999994 | Percent |
| June, 1986 | 52.4 | + 0.7 | Percent |
| July, 1986 | 57.4 | + 5 | Percent |
| August, 1986 | 59.9 | + 2.5 | Percent |
| September, 1986 | 60.5 | + 0.6 | Percent |
| October, 1986 | 57.8 | -2.7 | Percent |
| November, 1986 | 56.9 | -0.9 | Percent |
| December, 1986 | 62.2 | + 5.3 | Percent |
| January, 1987 | 61.6 | -0.6 | Percent |
| February, 1987 | 62.4 | + 0.8 | Percent |
| March, 1987 | 56.7 | -5.7 | Percent |
| April, 1987 | 52.2 | -4.5 | Percent |
| May, 1987 | 51.6 | -0.6 | Percent |
| June, 1987 | 56.8 | + 5.2 | Percent |
| July, 1987 | 58.8 | + 2 | Percent |
| August, 1987 | 60.2 | + 1.4 | Percent |
| September, 1987 | 59.7 | -0.5 | Percent |
| October, 1987 | 53.1 | -6.6 | Percent |
| November, 1987 | 55.6 | + 2.5 | Percent |
| December, 1987 | 60.3 | + 4.7 | Percent |
| January, 1988 | 64.1 | + 3.8 | Percent |
| February, 1988 | 65.4 | + 1.3 | Percent |
| March, 1988 | 62.8 | -2.6 | Percent |
| April, 1988 | 59.3 | -3.5 | Percent |
| May, 1988 | 57.5 | -1.8 | Percent |
| June, 1988 | 64.4 | + 6.9 | Percent |
| July, 1988 | 70.7 | + 6.3 | Percent |
| August, 1988 | 69.5 | -1.2 | Percent |
| September, 1988 | 67.9 | -1.6 | Percent |
| October, 1988 | 60.4 | -7.5 | Percent |
| November, 1988 | 58 | -2.4 | Percent |
| December, 1988 | 62.5 | + 4.5 | Percent |
| January, 1989 | 65.8 | + 3.3 | Percent |
| February, 1989 | 60.9 | -4.9 | Percent |
| March, 1989 | 54.9 | -6 | Percent |
| April, 1989 | 48 | -6.9 | Percent |
| May, 1989 | 53.1 | + 5.1 | Percent |
| June, 1989 | 61.5 | + 8.4 | Percent |
| July, 1989 | 72.3 | + 10.8 | Percent |
| August, 1989 | 75.2 | + 2.9 | Percent |
| September, 1989 | 63.4 | -11.8 | Percent |
| October, 1989 | 59.6 | -3.8 | Percent |
| November, 1989 | 61.4 | + 1.8 | Percent |
| December, 1989 | 69.5 | + 8.1 | Percent |
| January, 1990 | 75.5 | + 6 | Percent |
| February, 1990 | 75.7 | + 0.2 | Percent |
| March, 1990 | 62.4 | -13.3 | Percent |
| April, 1990 | 53.3 | -9.1 | Percent |
| May, 1990 | 57.5 | + 4.2 | Percent |
| June, 1990 | 64.1 | + 6.6 | Percent |
| July, 1990 | 71.7 | + 7.6 | Percent |
| August, 1990 | 74.6 | + 2.9 | Percent |
| September, 1990 | 67.5 | -7.1 | Percent |
| October, 1990 | 58.5 | -9 | Percent |
| November, 1990 | 62.8 | + 4.3 | Percent |
| December, 1990 | 69.6 | + 6.8 | Percent |
| January, 1991 | 73.4 | + 3.8 | Percent |
| February, 1991 | 71.5 | -1.9 | Percent |
| March, 1991 | 66.3 | -5.2 | Percent |
| April, 1991 | 58.1 | -8.2 | Percent |
| May, 1991 | 63.1 | + 5 | Percent |
| June, 1991 | 75.6 | + 12.5 | Percent |
| July, 1991 | 82 | + 6.4 | Percent |
| August, 1991 | 78.9 | -3.1 | Percent |
| September, 1991 | 72.3 | -6.6 | Percent |
| October, 1991 | 64.2 | -8.1 | Percent |
| November, 1991 | 64.6 | + 0.39999999999999 | Percent |
| December, 1991 | 72.3 | + 7.7 | Percent |
| January, 1992 | 78.1 | + 5.8 | Percent |
| February, 1992 | 76.3 | -1.8 | Percent |
| March, 1992 | 62 | -14.3 | Percent |
| April, 1992 | 59.1 | -2.9 | Percent |
| May, 1992 | 61.7 | + 2.6 | Percent |
| June, 1992 | 71.5 | + 9.8 | Percent |
| July, 1992 | 75.8 | + 4.3 | Percent |
| August, 1992 | 79.3 | + 3.5 | Percent |
| September, 1992 | 71.1 | -8.2 | Percent |
| October, 1992 | 65.9 | -5.2 | Percent |
| November, 1992 | 70.9 | + 5 | Percent |
| December, 1992 | 78.9 | + 8 | Percent |
| January, 1993 | 81.1 | + 2.2 | Percent |
| February, 1993 | 78 | -3.1 | Percent |
| March, 1993 | 64 | -14 | Percent |
| April, 1993 | 60.7 | -3.3 | Percent |
| May, 1993 | 68.4 | + 7.7 | Percent |
| June, 1993 | 73.8 | + 5.4 | Percent |
| July, 1993 | 76.7 | + 2.9 | Percent |
| August, 1993 | 76.3 | -0.40000000000001 | Percent |
| September, 1993 | 70.1 | -6.2 | Percent |
| October, 1993 | 60.2 | -9.9 | Percent |
| November, 1993 | 65.7 | + 5.5 | Percent |
| December, 1993 | 72.1 | + 6.4 | Percent |
| January, 1994 | 77.1 | + 5 | Percent |
| February, 1994 | 74.9 | -2.2 | Percent |
| March, 1994 | 66.5 | -8.4 | Percent |
| April, 1994 | 60.7 | -5.8 | Percent |
| May, 1994 | 65.9 | + 5.2 | Percent |
| June, 1994 | 72.6 | + 6.7 | Percent |
| July, 1994 | 80.1 | + 7.5 | Percent |
| August, 1994 | 81.5 | + 1.4 | Percent |
| September, 1994 | 77.9 | -3.6 | Percent |
| October, 1994 | 68.6 | -9.3 | Percent |
| November, 1994 | 77.4 | + 8.8 | Percent |
| December, 1994 | 82 | + 4.6 | Percent |
| January, 1995 | 85.9 | + 3.9 | Percent |
| February, 1995 | 77.8 | -8.1 | Percent |
| March, 1995 | 70.3 | -7.5 | Percent |
| April, 1995 | 69.2 | -1.1 | Percent |
| May, 1995 | 73.7 | + 4.5 | Percent |
| June, 1995 | 79 | + 5.3 | Percent |
| July, 1995 | 83.8 | + 4.8 | Percent |
| August, 1995 | 83.3 | -0.5 | Percent |
| September, 1995 | 77.7 | -5.6 | Percent |
| October, 1995 | 73.2 | -4.5 | Percent |
| November, 1995 | 73.6 | + 0.39999999999999 | Percent |
| December, 1995 | 80.8 | + 7.2 | Percent |
| January, 1996 | 85 | + 4.2 | Percent |
| February, 1996 | 79.7 | -5.3 | Percent |
| March, 1996 | 73.9 | -5.8 | Percent |
| April, 1996 | 69.4 | -4.5 | Percent |
| May, 1996 | 74.1 | + 4.7 | Percent |
| June, 1996 | 79.1 | + 5 | Percent |
| July, 1996 | 81.2 | + 2.1 | Percent |
| August, 1996 | 81.9 | + 0.7 | Percent |
| September, 1996 | 75.1 | -6.8 | Percent |
| October, 1996 | 67.3 | -7.8 | Percent |
| November, 1996 | 71.8 | + 4.5 | Percent |
| December, 1996 | 76.2 | + 4.4 | Percent |
| January, 1997 | 78.6 | + 2.4 | Percent |
| February, 1997 | 74.8 | -3.8 | Percent |
| March, 1997 | 67.2 | -7.6 | Percent |
| April, 1997 | 61.9 | -5.3 | Percent |
| May, 1997 | 62.7 | + 0.8 | Percent |
| June, 1997 | 71.8 | + 9.1 | Percent |
| July, 1997 | 76.5 | + 4.7 | Percent |
| August, 1997 | 82.3 | + 5.8 | Percent |
| September, 1997 | 70.9 | -11.4 | Percent |
| October, 1997 | 63.3 | -7.6 | Percent |
| November, 1997 | 69 | + 5.7 | Percent |
| December, 1997 | 74.8 | + 5.8 | Percent |
| January, 1998 | 78 | + 3.2 | Percent |
| February, 1998 | 76.1 | -1.9 | Percent |
| March, 1998 | 72.4 | -3.7 | Percent |
| April, 1998 | 66.2 | -6.2 | Percent |
| May, 1998 | 69.4 | + 3.2 | Percent |
| June, 1998 | 77.6 | + 8.2 | Percent |
| July, 1998 | 85.1 | + 7.5 | Percent |
| August, 1998 | 83.6 | -1.5 | Percent |
| September, 1998 | 81.8 | -1.8 | Percent |
| October, 1998 | 79.5 | -2.3 | Percent |
| November, 1998 | 82.1 | + 2.6 | Percent |
| December, 1998 | 86.5 | + 4.4 | Percent |
| January, 1999 | 90.2 | + 3.7 | Percent |
| February, 1999 | 87.4 | -2.8 | Percent |
| March, 1999 | 80.8 | -6.6 | Percent |
| April, 1999 | 68.8 | -12 | Percent |
| May, 1999 | 76.9 | + 8.1 | Percent |
| June, 1999 | 88.4 | + 11.5 | Percent |
| July, 1999 | 92.1 | + 3.7 | Percent |
| August, 1999 | 94.1 | + 2 | Percent |
| September, 1999 | 86.9 | -7.2 | Percent |
| October, 1999 | 76.7 | -10.2 | Percent |
| November, 1999 | 86.6 | + 9.9 | Percent |
| December, 1999 | 94.4 | + 7.8 | Percent |
| January, 2000 | 93.8 | -0.60000000000001 | Percent |
| February, 2000 | 91 | -2.8 | Percent |
| March, 2000 | 83.5 | -7.5 | Percent |
| April, 2000 | 80.2 | -3.3 | Percent |
| May, 2000 | 84.8 | + 4.6 | Percent |
| June, 2000 | 92.1 | + 7.3 | Percent |
| July, 2000 | 95.4 | + 3.3 | Percent |
| August, 2000 | 93.8 | -1.6 | Percent |
| September, 2000 | 87.8 | -6 | Percent |
| October, 2000 | 76.2 | -11.6 | Percent |
| November, 2000 | 85 | + 8.8 | Percent |
| December, 2000 | 93.2 | + 8.2 | Percent |
| January, 2001 | 94.1 | + 0.89999999999999 | Percent |
| February, 2001 | 92.9 | -1.2 | Percent |
| March, 2001 | 85.1 | -7.8 | Percent |
| April, 2001 | 79.2 | -5.9 | Percent |
| May, 2001 | 84.2 | + 5 | Percent |
| June, 2001 | 96.3 | + 12.1 | Percent |
| July, 2001 | 94.7 | -1.6 | Percent |
| August, 2001 | 93.7 | -1 | Percent |
| September, 2001 | 89.7 | -4 | Percent |
| October, 2001 | 82.8 | -6.9 | Percent |
| November, 2001 | 88.2 | + 5.4 | Percent |
| December, 2001 | 92.3 | + 4.1 | Percent |
| January, 2002 | 96.6 | + 4.3 | Percent |
| February, 2002 | 93 | -3.6 | Percent |
| March, 2002 | 85.9 | -7.1 | Percent |
| April, 2002 | 82.3 | -3.6 | Percent |
| May, 2002 | 85.9 | + 3.6 | Percent |
| June, 2002 | 93.4 | + 7.5 | Percent |
| July, 2002 | 95.9 | + 2.5 | Percent |
| August, 2002 | 96.4 | + 0.5 | Percent |
| September, 2002 | 90.8 | -5.6 | Percent |
| October, 2002 | 82.4 | -8.4 | Percent |
| November, 2002 | 86.6 | + 4.2 | Percent |
| December, 2002 | 93.9 | + 7.3 | Percent |
| January, 2003 | 93.8 | -0.10000000000001 | Percent |
| February, 2003 | 91.4 | -2.4 | Percent |
| March, 2003 | 81.2 | -10.2 | Percent |
| April, 2003 | 79.5 | -1.7 | Percent |
| May, 2003 | 84.3 | + 4.8 | Percent |
| June, 2003 | 89.9 | + 5.6 | Percent |
| July, 2003 | 94.4 | + 4.5 | Percent |
| August, 2003 | 93.5 | -0.90000000000001 | Percent |
| September, 2003 | 89 | -4.5 | Percent |
| October, 2003 | 81.3 | -7.7 | Percent |
| November, 2003 | 83.4 | + 2.1 | Percent |
| December, 2003 | 93 | + 9.6 | Percent |
| January, 2004 | 95.5 | + 2.5 | Percent |
| February, 2004 | 92.4 | -3.1 | Percent |
| March, 2004 | 85.4 | -7 | Percent |
| April, 2004 | 81.7 | -3.7 | Percent |
| May, 2004 | 87.6 | + 5.9 | Percent |
| June, 2004 | 94.4 | + 6.8 | Percent |
| July, 2004 | 97.1 | + 2.7 | Percent |
| August, 2004 | 95.9 | -1.2 | Percent |
| September, 2004 | 91.9 | -4 | Percent |
| October, 2004 | 84.4 | -7.5 | Percent |
| November, 2004 | 82.2 | -2.2 | Percent |
| December, 2004 | 92.6 | + 10.4 | Percent |
| January, 2005 | 93.9 | + 1.3 | Percent |
| February, 2005 | 90.7 | -3.2 | Percent |
| March, 2005 | 82.7 | -8 | Percent |
| April, 2005 | 77.1 | -5.6 | Percent |
| May, 2005 | 84.6 | + 7.5 | Percent |
| June, 2005 | 91.9 | + 7.3 | Percent |
| July, 2005 | 95.5 | + 3.6 | Percent |
| August, 2005 | 96 | + 0.5 | Percent |
| September, 2005 | 92.7 | -3.3 | Percent |
| October, 2005 | 82.3 | -10.4 | Percent |
| November, 2005 | 87.4 | + 5.1 | Percent |
| December, 2005 | 96.4 | + 9 | Percent |
| January, 2006 | 96.3 | -0.10000000000001 | Percent |
| February, 2006 | 92.9 | -3.4 | Percent |
| March, 2006 | 85.4 | -7.5 | Percent |
| April, 2006 | 79.7 | -5.7 | Percent |
| May, 2006 | 84.1 | + 4.4 | Percent |
| June, 2006 | 94.7 | + 10.6 | Percent |
| July, 2006 | 96.7 | + 2 | Percent |
| August, 2006 | 96.5 | -0.2 | Percent |
| September, 2006 | 92.3 | -4.2 | Percent |
| October, 2006 | 77 | -15.3 | Percent |
| November, 2006 | 85 | + 8 | Percent |
| December, 2006 | 94.4 | + 9.4 | Percent |
| January, 2007 | 99.2 | + 4.8 | Percent |
| February, 2007 | 96.8 | -2.4 | Percent |
| March, 2007 | 86.2 | -10.6 | Percent |
| April, 2007 | 79.4 | -6.8 | Percent |
| May, 2007 | 87.2 | + 7.8 | Percent |
| June, 2007 | 95.5 | + 8.3 | Percent |
| July, 2007 | 97.5 | + 2 | Percent |
| August, 2007 | 97.5 | 0 | Percent |
| September, 2007 | 93.6 | -3.9 | Percent |
| October, 2007 | 82.7 | -10.9 | Percent |
| November, 2007 | 89.9 | + 7.2 | Percent |
| December, 2007 | 96.5 | + 6.6 | Percent |
| January, 2008 | 94.4 | -2.1 | Percent |
| February, 2008 | 92.9 | -1.5 | Percent |
| March, 2008 | 86.3 | -6.6 | Percent |
| April, 2008 | 79 | -7.3 | Percent |
| May, 2008 | 86.5 | + 7.5 | Percent |
| June, 2008 | 96.9 | + 10.4 | Percent |
| July, 2008 | 99.1 | + 2.2 | Percent |
| August, 2008 | 96.9 | -2.2 | Percent |
| September, 2008 | 92.4 | -4.5 | Percent |
| October, 2008 | 83.8 | -8.6 | Percent |
| November, 2008 | 87.4 | + 3.6 | Percent |
| December, 2008 | 97.3 | + 9.9 | Percent |
| January, 2009 | 98.6 | + 1.3 | Percent |
| February, 2009 | 94.6 | -4 | Percent |
| March, 2009 | 89.5 | -5.1 | Percent |
| April, 2009 | 81.7 | -7.8 | Percent |
| May, 2009 | 87 | + 5.3 | Percent |
| June, 2009 | 95.9 | + 8.9 | Percent |
| July, 2009 | 97.1 | + 1.2 | Percent |
| August, 2009 | 96.1 | -1 | Percent |
| September, 2009 | 90.4 | -5.7 | Percent |
| October, 2009 | 77.2 | -13.2 | Percent |
| November, 2009 | 81.2 | + 4 | Percent |
| December, 2009 | 94.1 | + 12.9 | Percent |
| January, 2010 | 96.4 | + 2.3 | Percent |
| February, 2010 | 96 | -0.40000000000001 | Percent |
| March, 2010 | 85.9 | -10.1 | Percent |
| April, 2010 | 79.1 | -6.8 | Percent |
| May, 2010 | 88.6 | + 9.5 | Percent |
| June, 2010 | 93.8 | + 5.2 | Percent |
| July, 2010 | 95.5 | + 1.7 | Percent |
| August, 2010 | 95.1 | -0.40000000000001 | Percent |
| September, 2010 | 95.2 | + 0.10000000000001 | Percent |
| October, 2010 | 83.4 | -11.8 | Percent |
| November, 2010 | 86 | + 2.6 | Percent |
| December, 2010 | 97.9 | + 11.9 | Percent |
| January, 2011 | 96.6 | -1.3 | Percent |
| February, 2011 | 95.3 | -1.3 | Percent |
| March, 2011 | 87.2 | -8.1 | Percent |
| April, 2011 | 74.9 | -12.3 | Percent |
| May, 2011 | 75.7 | + 0.8 | Percent |
| June, 2011 | 89.5 | + 13.8 | Percent |
| July, 2011 | 96 | + 6.5 | Percent |
| August, 2011 | 94.6 | -1.4 | Percent |
| September, 2011 | 91.6 | -3 | Percent |
| October, 2011 | 84 | -7.6 | Percent |
| November, 2011 | 88.4 | + 4.4 | Percent |
| December, 2011 | 95.2 | + 6.8 | Percent |
| January, 2012 | 95.8 | + 0.59999999999999 | Percent |
| February, 2012 | 90.3 | -5.5 | Percent |
| March, 2012 | 81.7 | -8.6 | Percent |
| April, 2012 | 76.4 | -5.3 | Percent |
| May, 2012 | 82.1 | + 5.7 | Percent |
| June, 2012 | 89 | + 6.9 | Percent |
| July, 2012 | 91.3 | + 2.3 | Percent |
| August, 2012 | 91.8 | + 0.5 | Percent |
| September, 2012 | 88 | -3.8 | Percent |
| October, 2012 | 78.8 | -9.2 | Percent |
| November, 2012 | 77.3 | -1.5 | Percent |
| December, 2012 | 90.5 | + 13.2 | Percent |
| January, 2013 | 93.9 | + 3.4 | Percent |
| February, 2013 | 90.3 | -3.6 | Percent |
| March, 2013 | 83.4 | -6.9 | Percent |
| April, 2013 | 77.6 | -5.8 | Percent |
| May, 2013 | 83.3 | + 5.7 | Percent |
| June, 2013 | 93.1 | + 9.8 | Percent |
| July, 2013 | 95.6 | + 2.5 | Percent |
| August, 2013 | 96.7 | + 1.1 | Percent |
| September, 2013 | 92.2 | -4.5 | Percent |
| October, 2013 | 85.7 | -6.5 | Percent |
| November, 2013 | 91 | + 5.3 | Percent |
| December, 2013 | 96.6 | + 5.6 | Percent |
| January, 2014 | 99.1 | + 2.5 | Percent |
| February, 2014 | 94 | -5.1 | Percent |
| March, 2014 | 84.5 | -9.5 | Percent |
| April, 2014 | 78.8 | -5.7 | Percent |
| May, 2014 | 85.2 | + 6.4 | Percent |
| June, 2014 | 95.4 | + 10.2 | Percent |
| July, 2014 | 97.5 | + 2.1 | Percent |
| August, 2014 | 96.4 | -1.1 | Percent |
| September, 2014 | 94.6 | -1.8 | Percent |
| October, 2014 | 84.5 | -10.1 | Percent |
| November, 2014 | 91.3 | + 6.8 | Percent |
| December, 2014 | 99.6 | + 8.3 | Percent |
| January, 2015 | 101.3 | + 1.7 | Percent |
| February, 2015 | 95.8 | -5.5 | Percent |
| March, 2015 | 88 | -7.8 | Percent |
| April, 2015 | 84.3 | -3.7 | Percent |
| May, 2015 | 89.8 | + 5.5 | Percent |
| June, 2015 | 96.4 | + 6.6 | Percent |
| July, 2015 | 97.3 | + 0.89999999999999 | Percent |
| August, 2015 | 98.6 | + 1.3 | Percent |
| September, 2015 | 93.6 | -5 | Percent |
| October, 2015 | 82.5 | -11.1 | Percent |
| November, 2015 | 84.8 | + 2.3 | Percent |
| December, 2015 | 94.9 | + 10.1 | Percent |
| January, 2016 | 98.5 | + 3.6 | Percent |
| February, 2016 | 95.3 | -3.2 | Percent |
| March, 2016 | 89.9 | -5.4 | Percent |
| April, 2016 | 88.1 | -1.8 | Percent |
| May, 2016 | 90.5 | + 2.4 | Percent |
| June, 2016 | 94.2 | + 3.7 | Percent |
| July, 2016 | 94.5 | + 0.3 | Percent |
| August, 2016 | 96.1 | + 1.6 | Percent |
| September, 2016 | 90.9 | -5.2 | Percent |
| October, 2016 | 81.7 | -9.2 | Percent |
| November, 2016 | 90.9 | + 9.2 | Percent |
| December, 2016 | 96.7 | + 5.8 | Percent |
| January, 2017 | 98.7 | + 2 | Percent |
| February, 2017 | 95 | -3.7 | Percent |
| March, 2017 | 87.8 | -7.2 | Percent |
| April, 2017 | 79.2 | -8.6 | Percent |
| May, 2017 | 82.8 | + 3.6 | Percent |
| June, 2017 | 93.5 | + 10.7 | Percent |
| July, 2017 | 96.2 | + 2.7 | Percent |
| August, 2017 | 97.7 | + 1.5 | Percent |
| September, 2017 | 95 | -2.7 | Percent |
| October, 2017 | 89 | -6 | Percent |
| November, 2017 | 92.9 | + 3.9 | Percent |
| December, 2017 | 99.4 | + 6.5 | Percent |
| January, 2018 | 100.6 | + 1.2 | Percent |
| February, 2018 | 96.7 | -3.9 | Percent |
| March, 2018 | 90.3 | -6.4 | Percent |
| April, 2018 | 82.4 | -7.9 | Percent |
| May, 2018 | 90.7 | + 8.3 | Percent |
| June, 2018 | 97.1 | + 6.4 | Percent |
| July, 2018 | 97.7 | + 0.60000000000001 | Percent |
| August, 2018 | 97.4 | -0.3 | Percent |
| September, 2018 | 90.3 | -7.1 | Percent |
| October, 2018 | 80.4 | -9.9 | Percent |
| November, 2018 | 89.3 | + 8.9 | Percent |
| December, 2018 | 96.9 | + 7.6 | Percent |
| January, 2019 | 99.6 | + 2.7 | Percent |
| February, 2019 | 96.8 | -2.8 | Percent |
| March, 2019 | 88 | -8.8 | Percent |
| April, 2019 | 84.5 | -3.5 | Percent |
| May, 2019 | 90.8 | + 6.3 | Percent |
| June, 2019 | 96.6 | + 5.8 | Percent |
| July, 2019 | 98.1 | + 1.5 | Percent |
| August, 2019 | 97.7 | -0.39999999999999 | Percent |
| September, 2019 | 93.1 | -4.6 | Percent |
| October, 2019 | 85 | -8.1 | Percent |
| November, 2019 | 90.8 | + 5.8 | Percent |
| December, 2019 | 100.1 | + 9.3 | Percent |
| January, 2020 | 101.6 | + 1.5 | Percent |
| February, 2020 | 96.6 | -5 | Percent |
| March, 2020 | 87.7 | -8.9 | Percent |
| April, 2020 | 83.8 | -3.9 | Percent |
| May, 2020 | 89.1 | + 5.3 | Percent |
| June, 2020 | 96.1 | + 7 | Percent |
| July, 2020 | 96 | -0.099999999999994 | Percent |
| August, 2020 | 95.9 | -0.099999999999994 | Percent |
| September, 2020 | 94.6 | -1.3 | Percent |
| October, 2020 | 82.6 | -12 | Percent |
| November, 2020 | 88.8 | + 6.2 | Percent |
| December, 2020 | 97.3 | + 8.5 | Percent |
| January, 2021 | 100.2 | + 2.9 | Percent |
| February, 2021 | 97.1 | -3.1 | Percent |
| March, 2021 | 88.8 | -8.3 | Percent |
| Year | Year Open - Year Close | Year Min - Year Max | Year Average | Year Change |
|---|---|---|---|---|
| 2021 | 100.2 - 88.8 | 88.8 - 100.2 | 95.37 | -11.4 |
| 2020 | 101.6 - 97.3 | 82.6 - 101.6 | 92.51 | -4.3 |
| 2019 | 99.6 - 100.1 | 84.5 - 100.1 | 93.43 | + 0.5 |
| 2018 | 100.6 - 96.9 | 80.4 - 100.6 | 92.48 | -3.7 |
| 2017 | 98.7 - 99.4 | 79.2 - 99.4 | 92.27 | + 0.7 |
| 2016 | 98.5 - 96.7 | 81.7 - 98.5 | 92.28 | -1.8 |
| 2015 | 101.3 - 94.9 | 82.5 - 101.3 | 92.28 | -6.4 |
| 2014 | 99.1 - 99.6 | 78.8 - 99.6 | 91.74 | + 0.5 |
| 2013 | 93.9 - 96.6 | 77.6 - 96.7 | 89.95 | + 2.7 |
| 2012 | 95.8 - 90.5 | 76.4 - 95.8 | 86.08 | -5.3 |
| 2011 | 96.6 - 95.2 | 74.9 - 96.6 | 89.08 | -1.4 |
| 2010 | 96.4 - 97.9 | 79.1 - 97.9 | 91.08 | + 1.5 |
| 2009 | 98.6 - 94.1 | 77.2 - 98.6 | 90.28 | -4.5 |
| 2008 | 94.4 - 97.3 | 79 - 99.1 | 91.08 | + 2.9 |
| 2007 | 99.2 - 96.5 | 79.4 - 99.2 | 91.83 | -2.7 |
| 2006 | 96.3 - 94.4 | 77 - 96.7 | 89.58 | -1.9 |
| 2005 | 93.9 - 96.4 | 77.1 - 96.4 | 89.27 | + 2.5 |
| 2004 | 95.5 - 92.6 | 81.7 - 97.1 | 90.09 | -2.9 |
| 2003 | 93.8 - 93 | 79.5 - 94.4 | 87.89 | -0.8 |
| 2002 | 96.6 - 93.9 | 82.3 - 96.6 | 90.26 | -2.7 |
| 2001 | 94.1 - 92.3 | 79.2 - 96.3 | 89.43 | -1.8 |
| 2000 | 93.8 - 93.2 | 76.2 - 95.4 | 88.07 | -0.6 |
| 1999 | 90.2 - 94.4 | 68.8 - 94.4 | 85.28 | + 4.2 |
| 1998 | 78 - 86.5 | 66.2 - 86.5 | 78.19 | + 8.5 |
| 1997 | 78.6 - 74.8 | 61.9 - 82.3 | 71.15 | -3.8 |
| 1996 | 85 - 76.2 | 67.3 - 85 | 76.23 | -8.8 |
| 1995 | 85.9 - 80.8 | 69.2 - 85.9 | 77.36 | -5.1 |
| 1994 | 77.1 - 82 | 60.7 - 82 | 73.77 | + 4.9 |
| 1993 | 81.1 - 72.1 | 60.2 - 81.1 | 70.59 | -9 |
| 1992 | 78.1 - 78.9 | 59.1 - 79.3 | 70.88 | + 0.8 |
| 1991 | 73.4 - 72.3 | 58.1 - 82 | 70.19 | -1.1 |
| 1990 | 75.5 - 69.6 | 53.3 - 75.7 | 66.1 | -5.9 |
| 1989 | 65.8 - 69.5 | 48 - 75.2 | 62.13 | + 3.7 |
| 1988 | 64.1 - 62.5 | 57.5 - 70.7 | 63.54 | -1.6 |
| 1987 | 61.6 - 60.3 | 51.6 - 62.4 | 57.42 | -1.3 |
| 1986 | 60.4 - 62.2 | 51.3 - 62.2 | 56.89 | + 1.8 |
| 1985 | 68.8 - 57.2 | 50.5 - 68.8 | 58.02 | -11.6 |
| 1984 | 62.5 - 59.6 | 48.6 - 64.8 | 56.36 | -2.9 |
| 1983 | 56.6 - 56.5 | 49.5 - 57.3 | 54.84 | -0.1 |
| 1982 | 61.6 - 54.6 | 51.9 - 61.6 | 56.58 | -7 |
| 1981 | 61.7 - 62.3 | 50.3 - 67.4 | 58.19 | + 0.6 |
| 1980 | 53.4 - 57.4 | 49.7 - 63.5 | 56.3 | + 4 |
| 1979 | 73.8 - 55.6 | 40.6 - 76.2 | 58.46 | -18.2 |
| 1978 | 75 - 67.2 | 49.7 - 75 | 64.52 | -7.8 |
| 1977 | 66.8 - 69 | 55.3 - 69 | 63.31 | + 2.2 |
| 1976 | 58.1 - 64.8 | 40 - 64.8 | 54.74 | + 6.7 |
| 1975 | 57.3 - 60.2 | 50.1 - 60.5 | 55.91 | + 2.9 |
| 1974 | 45 - 56 | 34.6 - 58.9 | 47.78 | + 11 |
| 1973 | 57.8 - 47.6 | 47.3 - 60.7 | 53.54 | -10.2 |