Year | Value | 2021 | 21.597047845565 | 2020 | 21.946045972165 | 2019 | 22.259420212328 | 2018 | 22.63362479092 | 2017 | 23.035704449176 | 2016 | 23.531275621439 | 2015 | 23.965466200716 | 2014 | 24.458986316378 | 2013 | 24.890531956413 | 2012 | 25.236320628278 | 2011 | 25.455112707512 | 2010 | 25.547363210238 | 2009 | 25.847186369736 | 2008 | 26.173622632533 | 2007 | 26.460662616044 | 2006 | 26.684233162072 | 2005 | 26.924280406189 | 2004 | 27.122690233599 | 2003 | 27.303314155534 | 2002 | 27.505238957336 | 2001 | 27.692842267935 | 2000 | 28.010210910341 | 1999 | 28.234578988354 | 1998 | 28.473352872991 | 1997 | 28.787564962352 | 1996 | 29.277480533094 | 1995 | 29.778977074673 | 1994 | 30.536072681925 | 1993 | 31.169565666655 | 1992 | 31.84038180766 | 1991 | 32.139698380773 | 1990 | 32.722971953888 | 1989 | 33.080362515804 | 1988 | 33.39599702882 | 1987 | 33.553979879932 | 1986 | 33.650563496067 | 1985 | 33.813568373237 | 1984 | 34.170448833935 | 1983 | 34.372364350049 | 1982 | 34.555267031766 | 1981 | 34.817413924113 | 1980 | 35.034594547604 | 1979 | 34.983624112411 | 1978 | 34.956509005914 | 1977 | 34.866770874727 | 1976 | 34.896715050385 | 1975 | 34.624957990592 | 1974 | 34.663016908774 | 1973 | 34.301748512142 | 1972 | 34.798765914548 | 1971 | 34.965190525069 | 1970 | 34.946043006308 | 1969 | 34.98906787956 | 1968 | 35.246321211694 | 1967 | 35.172294340032 | 1966 | 35.725006117916 | 1965 | 35.997219422204 | 1964 | 36.574077296922 | 1963 | 36.890548508401 | 1962 | 37.027628822891 | 1961 | 37.263874989808 | 1960 | 37.437644363692 |
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