Year | Value | 2021 | 8.4646020650658 | 2020 | 7.7860636907586 | 2019 | 6.5239683015349 | 2018 | 6.4866861696541 | 2017 | 6.4195688608631 | 2016 | 6.3895326376511 | 2015 | 6.2542295614832 | 2014 | 6.1453476458068 | 2013 | 6.1336660091331 | 2012 | 6.12990053327 | 2011 | 6.1149568144747 | 2010 | 6.2683121497147 | 2009 | 6.0504239514241 | 2008 | 6.0185801672097 | 2007 | 6.0219567976098 | 2006 | 5.963511622728 | 2005 | 5.9481482997547 | 2004 | 6.0135085701256 | 2003 | 6.0524950258804 | 2002 | 6.0458909817063 | 2001 | 6.0678061721401 | 2000 | 6.126519924286 | 1999 | 6.161413848331 | 1998 | 6.2683882265129 | 1997 | 6.3018180606458 | 1996 | 6.3616906569261 | 1995 | 6.4578005947602 | 1994 | 6.5184850181982 | 1993 | 6.6350284078061 | 1992 | 6.7348958283151 | 1991 | 6.8427804316548 | 1990 | 6.9599560438209 | 1989 | 7.0511472704369 | 1988 | 7.1825230953485 | 1987 | 7.3533041981389 | 1986 | 7.529211244913 | 1985 | 7.7805196842757 | 1984 | 7.9282504191412 | 1983 | 8.1128478749247 | 1982 | 8.3920604018823 | 1981 | 8.5318582243489 | 1980 | 8.7420914014195 | 1979 | 8.911103290184 | 1978 | 9.059871129866 | 1977 | 9.2108106406239 | 1976 | 9.4690901278674 | 1975 | 9.562945642482 | 1974 | 9.8151853017271 | 1973 | 10.014203429861 | 1972 | 10.278307724807 | 1971 | 10.488468047687 | 1970 | 11.002401202212 | 1969 | 11.025182845937 | 1968 | 11.264658555466 | 1967 | 11.518130603524 | 1966 | 11.783767395753 | 1965 | 12.083538434365 | 1964 | 12.36660584261 | 1963 | 12.69136896089 | 1962 | 12.994627573057 | 1961 | 13.322549081815 | 1960 | 13.704076243995 |
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