Year | Value | 2021 | 34.552117040562 | 2020 | 34.247607636528 | 2019 | 33.710830500793 | 2018 | 33.17405279855 | 2017 | 32.76757251303 | 2016 | 32.29311126218 | 2015 | 31.99426693859 | 2014 | 31.735078744618 | 2013 | 31.566531837752 | 2012 | 31.341333559937 | 2011 | 30.878618853388 | 2010 | 30.608429639701 | 2009 | 30.336505778382 | 2008 | 30.336505778382 | 2007 | 30.336505778382 | 2006 | 30.336505778382 | 2005 | 30.342170858826 | 2004 | 29.628370722864 | 2003 | 28.891910265126 | 2002 | 28.325402220711 | 2001 | 27.702243371856 | 2000 | 27.022433718559 | 1999 | 26.28597326082 | 1998 | 26.229322456379 | 1997 | 25.946068434172 | 1996 | 25.946068434172 | 1995 | 25.88941762973 | 1994 | 25.88941762973 | 1993 | 25.668479492409 | 1992 | 25.577838205302 | 1991 | 25.549512803082 | 1990 | 25.237933378654 | 1989 | 25.124631769771 | 1988 | 23.510083843191 | 1987 | 20.960797643327 | 1986 | 18.638114661228 | 1985 | 16.938590527986 | 1984 | 15.244731475187 | 1983 | 15.239066394743 | 1982 | 15.182415590301 | 1981 | 15.012463176977 | 1980 | 15.012463176977 | 1979 | 14.72920915477 | 1978 | 14.72920915477 | 1977 | 14.445955132563 | 1976 | 14.445955132563 | 1975 | 14.162701110356 | 1974 | 14.162701110356 | 1973 | 13.879447088149 | 1972 | 13.879447088149 | 1971 | 13.879447088149 | 1970 | 19.368910038523 | 1969 | 19.697484704283 | 1968 | 20.263992748697 | 1967 | 20.558576931792 | 1966 | 20.547246770904 | 1965 | 20.547246770904 | 1964 | 20.365964196692 | 1963 | 20.065714933152 | 1962 | 20.014729209155 | 1961 | 19.929753002493 |
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