Year | Value | 2021 | 10.54351434293 | 2020 | 11.275876179561 | 2019 | 12.604657191415 | 2018 | 12.975805817584 | 2017 | 14.25447424201 | 2016 | 14.986578474428 | 2015 | 14.033498992896 | 2014 | 15.387002486472 | 2013 | 14.943611720282 | 2012 | 16.083573417704 | 2011 | 15.23197768032 | 2010 | 14.324199392354 | 2009 | 14.442335828956 | 2008 | 14.635340362298 | 2007 | 14.646233658565 | 2006 | 14.628477295127 | 2005 | 14.874987847892 | 2004 | 14.850061362447 | 2003 | 15.002258646036 | 2002 | 15.406456931089 | 2001 | 15.851418532907 | 2000 | 16.368600397916 | 1999 | 16.907348468714 | 1998 | 17.783537716277 | 1997 | 18.628972447353 | 1996 | 19.065188509809 | 1995 | 19.313232651484 | 1994 | 19.887841071314 | 1993 | 20.323502954737 | 1992 | 20.596675174902 | 1991 | 21.75596184027 | 1990 | 22.797469300141 | 1989 | 23.303187735525 | 1988 | 24.018358930667 | 1987 | 24.839904728758 | 1986 | 24.357011382096 | 1985 | 23.59281715005 | 1984 | 23.041700231913 | 1983 | 23.403783099853 | 1982 | 25.034042487793 | 1981 | 24.13450600075 | 1980 | 22.280478842426 | 1979 | 22.030629466504 | 1978 | 22.36832679258 | 1977 | 22.892750014397 | 1976 | 23.734156929106 | 1975 | 26.180444251893 | 1974 | 27.674364214865 | 1973 | 30.230986768779 | 1972 | 31.787728631594 | 1971 | 32.553532285227 | 1970 | 34.755602033783 | 1969 | 35.401839107747 | 1968 | 36.642967439698 | 1967 | 35.610469194125 | 1966 | 36.556609263187 | 1965 | 38.816295446137 | 1964 | 39.893382237484 | 1963 | 43.146952561384 | 1962 | 38.539483941115 | 1961 | 24.407608223441 | 1960 | 26.638673741277 |
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