Year | Value | 2021 | 12.694836 | 2020 | 15.638799 | 2019 | 25.641745 | 2018 | 28.28048 | 2017 | 24.80375 | 2016 | 21.591025 | 2015 | 21.901645167149 | 2014 | 21.6623331878 | 2013 | 17.502418627731 | 2012 | 14.926 | 2011 | 14.826 | 2010 | 15.906 | 2009 | 4.317 | 2008 | 16.985 | 2007 | 16.572 | 2006 | 23.694 | 2005 | 31.624 | 2004 | 21.44 | 2003 | 19.091 | 2002 | 17.89 | 2001 | 18.346 | 2000 | 12.647 | 1999 | 15.3999996185 | 1998 | 18.7999992371 | 1997 | 16.7999992371 | 1996 | 16 | 1995 | 21 | 1994 | 24.2000007629 | 1993 | 21.2999992371 | 1992 | 20.2000007629 | 1991 | 24.2999992371 | 1990 | 14.6000003815 | 1989 | 23.1000003815 | 1988 | 13.8999996185 | 1987 | 13.3000001907 | 1986 | 7.6999998093 | 1985 | 21 | 1984 | 14.8999996185 | 1983 | 28.2000007629 | 1982 | 15.8999996185 | 1981 | 14.1999998093 | 1980 | 12.8999996185 | 1979 | 12.3000001907 | 1978 | 11.1999998093 | 1977 | 9 | 1976 | 9.1000003815 | 1975 | 7.1999998093 | 1974 | 6.5999999046 | 1973 | 5.1999998093 | 1972 | 4.1999998093 | 1971 | 3.7000000477 | 1970 | 3.0999999046 |
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