Year | Value | 2022 | 18.534376618645 | 2021 | 18.75949661358 | 2020 | 18.972280521013 | 2019 | 19.186413127184 | 2018 | 19.398931814544 | 2017 | 19.604749532645 | 2016 | 19.808447174332 | 2015 | 20.008752308117 | 2014 | 20.206411038336 | 2013 | 20.40005242475 | 2012 | 20.5946685186 | 2011 | 20.792088314776 | 2010 | 21.017451845608 | 2009 | 21.303227012239 | 2008 | 21.595794251521 | 2007 | 21.897455149889 | 2006 | 22.211343229847 | 2005 | 22.539213891659 | 2004 | 22.893296428793 | 2003 | 23.261637249259 | 2002 | 23.64548340901 | 2001 | 24.048527987785 | 2000 | 24.39767889876 | 1999 | 24.636320215674 | 1998 | 24.876308386282 | 1997 | 25.115558541783 | 1996 | 25.35539784548 | 1995 | 25.604537519427 | 1994 | 25.875147621893 | 1993 | 26.14753821059 | 1992 | 26.415074701987 | 1991 | 26.678795229863 | 1990 | 26.961724301479 | 1989 | 27.242113253588 | 1988 | 27.504959055528 | 1987 | 27.789189283325 | 1986 | 28.076222186129 | 1985 | 28.344144786143 | 1984 | 28.605713746771 | 1983 | 28.866150234746 | 1982 | 29.135761414288 | 1981 | 29.421477523811 | 1980 | 29.726677796664 | 1979 | 29.983713812322 | 1978 | 30.23970044728 | 1977 | 30.499504557991 | 1976 | 30.757216542544 | 1975 | 31.026859851232 | 1974 | 31.365550946816 | 1973 | 31.722056058523 | 1972 | 32.082379838469 | 1971 | 32.452344672076 | 1970 | 32.856875055502 | 1969 | 33.320155646876 | 1968 | 33.798094341931 | 1967 | 34.296333931606 | 1966 | 34.802582237096 | 1965 | 35.299453756301 | 1964 | 35.799437728805 | 1963 | 36.313579928597 | 1962 | 36.82747808444 | 1961 | 37.325417309105 | 1960 | 37.823351143826 |
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