Year | Value | 2022 | 2.5858676814208 | 2021 | 2.1925340393711 | 2020 | 1.9713982636962 | 2019 | 2.0061363091202 | 2018 | 2.2434344962884 | 2017 | 2.8443384495596 | 2016 | 2.79643556281 | 2015 | 2.5570908068691 | 2014 | 2.1165570614495 | 2013 | 2.1807719090984 | 2012 | 2.6866084684997 | 2011 | 2.3816345425043 | 2010 | 2.7865480606164 | 2009 | 3.0477055491766 | 2008 | 2.6833419205564 | 2007 | 2.6539828211589 | 2006 | 3.3151938003344 | 2005 | 3.0366544980482 | 2004 | 2.8345578046395 | 2003 | 2.4050402653569 | 2002 | 2.1745763661274 | 2001 | 2.4181792967932 | 2000 | 2.2950422215257 | 1999 | 2.4045517378011 | 1998 | 2.62907924769 | 1997 | 2.4988747250578 | 1996 | 2.2448645106428 | 1995 | 2.1541658849804 | 1994 | 2.0730100051262 | 1993 | 1.7003612017497 | 1992 | 1.7893054443736 | 1991 | 2.1697079665705 | 1990 | 2.9426501253476 | 1989 | 4.5579804926896 | 1988 | 6.269777621033 | 1987 | 5.8891077886328 | 1986 | 6.0793359752371 | 1985 | 6.5124184403321 | 1984 | 6.354853844404 | 1983 | 7.0970806500596 | 1982 | 7.9068906383974 | 1981 | 8.1903808234271 | 1980 | 5.3431501854237 | 1979 | 5.7972470280978 | 1978 | 11.113205091091 | 1977 | 10.189830148982 | 1976 | 11.247972334623 | 1975 | 12.069192909256 | 1974 | 8.7503502475082 | 1973 | 1.8647054187636 | 1972 | 2.2753702776477 | 1971 | 3.0470124780035 | 1970 | 5.8569032909625 | 1969 | 5.9690541955316 | 1968 | 5.176363590904 | 1967 | 4.4579917613823 | 1966 | 3.8189953679917 | 1965 | 3.2495249044447 | 1964 | 2.8818267477576 | 1963 | 2.5903569644736 | 1962 | 2.307410877121 | 1961 | 2.3466421816608 | 1960 | 2.2949088330197 |
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