Year | Value | 2018 | 4.58628 | 2017 | 2.83938 | 2016 | 4.506984 | 2015 | 1.396 | 2009 | 10.272 | 2008 | 16.25 | 2007 | 15.655 | 2006 | 15.348 | 2005 | 15.823 | 2004 | 37.698 | 2003 | 48.859 | 2002 | 56.588 | 2001 | 26.391 | 2000 | 29.196 | 1999 | 29.5 | 1998 | 23.7999992371 | 1997 | 20.8999996185 | 1996 | 24.8999996185 | 1995 | 21.7999992371 | 1994 | 19.7999992371 | 1993 | 19.7999992371 | 1992 | 18.3999996185 | 1991 | 19.7000007629 | 1990 | 18.7999992371 | 1989 | 16.2999992371 | 1988 | 20.6000003815 | 1987 | 24.2000007629 | 1986 | 18.8999996185 | 1985 | 19.1000003815 | 1984 | 19.6000003815 | 1983 | 16.6000003815 | 1982 | 9.6999998093 | 1981 | 9.8999996185 | 1980 | 9.3999996185 | 1979 | 10.6999998093 | 1978 | 13.1999998093 | 1977 | 11.6000003815 | 1976 | 11 | 1975 | 10.8999996185 | 1974 | 9.6999998093 | 1973 | 5.8000001907 | 1972 | 4.8000001907 | 1971 | 3.2999999523 | 1970 | 2.5 |
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