Year | Value | 2021 | 2.464604090194 | 2020 | 2.464604090194 | 2019 | 2.464604090194 | 2018 | 2.464604090194 | 2017 | 2.4774538590604 | 2016 | 2.621644295302 | 2015 | 2.6287483275179 | 2014 | 2.6287483275179 | 2013 | 2.6287483275179 | 2012 | 2.6287483275179 | 2011 | 2.6287483275179 | 2010 | 2.6392423328174 | 2009 | 2.6235013248682 | 2008 | 2.6235013248682 | 2007 | 3.5758323057953 | 2006 | 3.9693575045255 | 2005 | 4.3812472125298 | 2004 | 4.1451320932917 | 2003 | 3.9447236180905 | 2002 | 3.9195979899498 | 2001 | 3.8944723618091 | 2000 | 3.8693467336683 | 1999 | 3.8442211055276 | 1998 | 3.8442211055276 | 1997 | 3.8442211055276 | 1996 | 3.7939698492462 | 1995 | 3.6683417085427 | 1994 | 3.5175879396985 | 1993 | 2.9107719966612 | 1992 | 2.8893692613916 | 1991 | 2.8893692613916 | 1990 | 2.8893692613916 | 1989 | 2.8465637908525 | 1988 | 3.017785673009 | 1987 | 3.1247993493568 | 1986 | 3.1033966140873 | 1985 | 3.1033966140873 | 1984 | 3.1033966140873 | 1983 | 3.1033966140873 | 1982 | 2.8893692613916 | 1981 | 2.7823555850438 | 1980 | 2.7823555850438 | 1979 | 2.6753419086959 | 1978 | 2.5683282323481 | 1977 | 2.5683282323481 | 1976 | 2.5683282323481 | 1975 | 2.4613145560003 | 1974 | 2.4613145560003 | 1973 | 2.3543008796524 | 1972 | 2.3543008796524 | 1971 | 2.3543008796524 | 1970 | 2.3543008796524 | 1969 | 2.1402735269567 | 1968 | 2.1402735269567 | 1967 | 2.1402735269567 | 1966 | 2.1402735269567 | 1965 | 2.1402735269567 | 1964 | 2.1402735269567 | 1963 | 2.1402735269567 | 1962 | 2.1402735269567 | 1961 | 2.1402735269567 |
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