Year | Value | 2022 | 2.6965205245424 | 2021 | 2.7278721066027 | 2020 | 2.8205108633137 | 2019 | 2.8357259598969 | 2018 | 2.7557707608628 | 2017 | 2.7210654179362 | 2016 | 2.6642373064387 | 2015 | 2.5490000836636 | 2014 | 2.5037274678823 | 2013 | 2.5616786537627 | 2012 | 2.758538993733 | 2011 | 2.8594802516101 | 2010 | 2.8771475921054 | 2009 | 2.894152653681 | 2008 | 2.906118753281 | 2007 | 3.0084236970448 | 2006 | 3.0384299128755 | 2005 | 2.9188562478256 | 2004 | 2.9101559438856 | 2003 | 3.0735663867653 | 2002 | 3.0152383502151 | 2001 | 2.7002064959393 | 2000 | 2.6876072757884 | 1999 | 2.7925192139909 | 1998 | 2.7505491259995 | 1997 | 2.8348594888818 | 1996 | 2.9563831316145 | 1995 | 2.8819205510951 | 1994 | 2.9155541788622 | 1993 | 3.1724564023742 | 1992 | 3.0036964673581 | 1991 | 2.5432512143543 | 1990 | 2.5529450486068 | 1989 | 2.6326576939418 | 1988 | 2.5718912472558 | 1987 | 2.6130430066626 | 1986 | 2.5935700974792 | 1985 | 2.6755927761332 | 1984 | 2.6769340043503 | 1983 | 2.6356217186293 | 1982 | 2.3514651583652 | 1981 | 1.9174147230316 | 1980 | 2.2098580568311 | 1979 | 2.7805832350614 | 1978 | 2.7233093618439 | 1977 | 2.5528562999076 | 1976 | 2.6346256694395 | 1975 | 2.6502559596927 | 1974 | 2.6505751418644 | 1973 | 2.5864463208772 | 1972 | 2.5768313096614 | 1971 | 2.6403897535751 | 1970 | 2.6521485500537 | 1969 | 2.648320931999 | 1968 | 2.657150997528 | 1967 | 2.5970763076052 | 1966 | 2.534039908488 | 1965 | 2.5225143501231 | 1964 | 2.4721470177815 | 1963 | 2.4095155843133 | 1962 | 2.374211937589 | 1961 | 2.3362071788651 |
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