Year | Value | 2022 | 23.033446931895 | 2021 | 21.581759496415 | 2020 | 22.468286789258 | 2019 | 21.932013415646 | 2018 | 22.978361068723 | 2017 | 23.923213201681 | 2016 | 37.612849787134 | 2015 | 22.689444117931 | 2014 | 24.491959981956 | 2013 | 21.656785501489 | 2012 | 21.503307076745 | 2011 | 20.582177425735 | 2010 | 20.226437993308 | 2009 | 19.933538648121 | 2008 | 22.797774575151 | 2007 | 25.958491784 | 2006 | 26.897137581756 | 2005 | 27.242993122802 | 2004 | 24.766320966813 | 2003 | 23.677082333855 | 2002 | 22.592711821486 | 2001 | 22.764067373412 | 2000 | 25.105572588889 | 1999 | 25.860394313446 | 1998 | 23.955378679797 | 1997 | 21.996903575994 | 1996 | 23.447836633502 | 1995 | 22.513347345255 | 1994 | 22.254788284014 | 1993 | 22.506350565729 | 1992 | 23.160955195049 | 1991 | 22.856920901229 | 1990 | 23.507507254155 | 1989 | 23.44165487038 | 1988 | 22.305864465736 | 1987 | 20.693834019625 | 1986 | 20.30388989404 | 1985 | 20.104447601205 | 1984 | 20.944708045997 | 1983 | 20.573260297607 | 1982 | 22.950691940639 | 1981 | 22.551618525544 | 1980 | 21.211639470305 | 1979 | 21.897958218155 | 1978 | 21.148895153053 | 1977 | 20.748796351236 | 1976 | 21.77024548985 | 1975 | 22.882332185055 | 1974 | 23.771272812993 | 1973 | 22.873684402742 | 1972 | 22.818141704573 |
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