| Year | Value | | 2021 | 0.022018 | | 2020 | 0.10855 | | 2019 | 0.047589211773818 | | 2018 | 0.100011 | | 2012 | 0.94143637223328 | | 2011 | 1.2314967659627 | | 2010 | 0.925987427 | | 2001 | 1.603 | | 2000 | 2.323 | | 1999 | 2.2000000477 | | 1998 | 3.2999999523 | | 1997 | 3.2999999523 | | 1996 | 3.2999999523 | | 1995 | 3.0999999046 | | 1994 | 3 | | 1993 | 3 | | 1992 | 3 | | 1991 | 2.7999999523 | | 1990 | 2.7999999523 | | 1989 | 2.7999999523 | | 1988 | 2.5999999046 | | 1987 | 2.5 | | 1986 | 2.4000000954 | | 1985 | 2.2999999523 | | 1984 | 2.2999999523 | | 1983 | 2.2000000477 | | 1982 | 2.2000000477 | | 1981 | 2 | | 1980 | 0.8000000119 | | 1979 | 0.8000000119 | | 1978 | 0.8000000119 | | 1977 | 0.8000000119 | | 1976 | 0.8000000119 | | 1975 | 0.6999999881 | | 1974 | 1.3999999762 | | 1973 | 1.2999999523 | | 1972 | 1.2999999523 | | 1971 | 1.2999999523 | | 1970 | 1.2000000477 |
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