Year | Value | 2021 | 7.5052365060724 | 2020 | 7.3390522808686 | 2019 | 7.0984146684476 | 2018 | 7.2272287161734 | 2017 | 7.3862850918193 | 2016 | 7.5527239299854 | 2015 | 7.771825728997 | 2014 | 7.9406727263933 | 2013 | 8.1116288607388 | 2012 | 8.2759912675152 | 2011 | 8.4703122510194 | 2010 | 8.7986681717446 | 2009 | 9.0209502914542 | 2008 | 9.4378833217087 | 2007 | 9.5425774619129 | 2006 | 9.7721537323031 | 2005 | 10.077102056334 | 2004 | 10.410162392352 | 2003 | 10.633702004613 | 2002 | 10.940773516706 | 2001 | 11.207229183412 | 2000 | 11.486238834574 | 1999 | 11.792330612833 | 1998 | 12.588356255489 | 1997 | 12.597357047902 | 1996 | 12.986908632565 | 1995 | 13.124250547551 | 1994 | 14.107828229138 | 1993 | 13.906264168518 | 1992 | 14.33224158277 | 1991 | 14.669826803541 | 1990 | 14.495452282009 | 1989 | 14.723718577168 | 1988 | 15.70182837091 | 1987 | 15.437905422179 | 1986 | 15.902774590759 | 1985 | 16.452715024757 | 1984 | 16.774381623518 | 1983 | 16.858317194719 | 1982 | 16.387638459804 | 1981 | 16.582782883212 | 1980 | 16.808987270644 | 1979 | 17.136077169401 | 1978 | 17.464656412623 | 1977 | 17.772248866481 | 1976 | 18.901073229668 | 1975 | 19.431428802569 | 1974 | 18.7402988455 | 1973 | 18.739520487832 | 1972 | 19.224822193449 | 1971 | 23.685597973088 | 1970 | 20.459961986399 | 1969 | 19.695861194327 | 1968 | 19.903184160036 | 1967 | 20.195642451481 | 1966 | 20.680722741682 | 1965 | 20.957312916962 | 1964 | 21.025351455999 | 1963 | 21.588976865445 | 1962 | 21.75653719392 | 1961 | 22.156166016041 | 1960 | 22.553003440394 |
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