Year | Value | 2021 | 20.27706066 | 2020 | 17.95563766 | 2019 | 22.980404 | 2018 | 13.728477402893 | 2017 | 9.4855438198556 | 2016 | 9.008756313 | 2015 | 9.9347974863754 | 2014 | 8.7807255770769 | 2013 | 7.993202 | 2012 | 12.300314949538 | 2011 | 17.412461714315 | 2010 | 11.236595977 | 2009 | 6.871 | 2008 | 8.755 | 2007 | 8.718 | 2006 | 10.714 | 2005 | 25.295 | 2004 | 24.371 | 2003 | 24.522 | 2002 | 14.922 | 2001 | 13.568 | 2000 | 15.341 | 1999 | 19.7999992371 | 1998 | 43 | 1997 | 47.0999984741 | 1996 | 46.5999984741 | 1995 | 48.9000015259 | 1994 | 28.3999996185 | 1993 | 10.1000003815 | 1992 | 6.8000001907 | 1991 | 5 | 1990 | 8.3999996185 | 1989 | 8.3999996185 | 1988 | 8.3000001907 | 1987 | 25.5 | 1986 | 27.7999992371 | 1985 | 41.5 | 1984 | 38 | 1983 | 17.2000007629 | 1982 | 27.6000003815 | 1981 | 43.7000007629 | 1980 | 37.5999984741 | 1979 | 33.9000015259 | 1978 | 43.0999984741 | 1977 | 27.6000003815 | 1976 | 4.0999999046 | 1975 | 2.5999999046 | 1974 | 2.4000000954 | 1973 | 2.9000000954 | 1972 | 2.7999999523 | 1971 | 2.5 | 1970 | 1.5 |
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