Year | Value | 2021 | 23.631267026734 | 2020 | 23.664268616951 | 2019 | 23.670230177187 | 2018 | 23.603365945177 | 2017 | 23.883825029161 | 2016 | 23.880151069393 | 2015 | 23.929934930697 | 2014 | 24.002767975313 | 2013 | 24.088727818405 | 2012 | 24.31846179849 | 2011 | 24.106120010266 | 2010 | 24.267620083607 | 2009 | 24.25316332726 | 2008 | 24.395813108623 | 2007 | 24.260888317782 | 2006 | 24.462777515785 | 2005 | 24.756378797325 | 2004 | 24.770435996545 | 2003 | 24.730763004818 | 2002 | 24.872854122309 | 2001 | 24.975119049403 | 2000 | 25.770825472119 | 1999 | 25.83235583304 | 1998 | 25.857254479769 | 1997 | 26.050200667341 | 1996 | 26.142569372545 | 1995 | 26.001890777188 | 1994 | 26.541807299461 | 1993 | 26.756940955807 | 1992 | 26.728620857064 | 1991 | 26.502946514598 | 1990 | 26.754443838627 | 1989 | 26.801996376712 | 1988 | 26.841333031254 | 1987 | 27.047725984516 | 1986 | 26.98739318314 | 1985 | 26.965318182912 | 1984 | 26.992870438836 | 1983 | 26.919080680311 | 1982 | 27.114763322277 | 1981 | 27.099327547961 | 1980 | 27.09220264266 | 1979 | 27.078843483954 | 1978 | 27.095262516722 | 1977 | 26.987144750393 | 1976 | 26.955689731861 | 1975 | 27.068455319905 | 1974 | 27.132701815062 | 1973 | 27.131700290337 | 1972 | 27.321219795329 | 1971 | 27.442200284943 | 1970 | 28.367186572991 | 1969 | 28.73195353619 | 1968 | 28.733903496071 | 1967 | 28.975657032759 | 1966 | 29.106387321776 | 1965 | 29.511522603354 | 1964 | 29.655238795406 | 1963 | 30.000589136815 | 1962 | 30.074148261673 | 1961 | 30.111653872994 |
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