| Year | Value | | 2000 | 0.535 | | 1999 | 0.5 | | 1998 | 0.400000006 | | 1997 | 9 | | 1996 | 9 | | 1995 | 9 | | 1994 | 7 | | 1993 | 3.7999999523 | | 1992 | 6.8000001907 | | 1991 | 3.5999999046 | | 1990 | 3.5999999046 | | 1989 | 1.7999999523 | | 1988 | 1.2000000477 | | 1987 | 1.1000000238 | | 1986 | 1 | | 1985 | 1.3999999762 | | 1984 | 1.2999999523 | | 1983 | 1.1000000238 | | 1982 | 1 | | 1981 | 1.1000000238 | | 1980 | 1.2999999523 | | 1979 | 2.0999999046 | | 1978 | 2 | | 1977 | 2 | | 1976 | 2 | | 1975 | 1.8999999762 | | 1974 | 1.8999999762 | | 1973 | 1.8999999762 | | 1972 | 0.8999999762 | | 1971 | 0.8999999762 | | 1970 | 0.8000000119 |
|