Year | Value | 2021 | 37.479641945236 | 2020 | 37.474976279221 | 2019 | 37.424255251596 | 2018 | 37.436843188981 | 2017 | 37.421916887469 | 2016 | 37.398702125174 | 2015 | 37.382569845964 | 2014 | 37.335563920857 | 2013 | 37.357106264602 | 2012 | 37.301721006948 | 2011 | 37.292555733839 | 2010 | 37.261481279759 | 2009 | 37.145435218788 | 2008 | 37.110174308055 | 2007 | 37.156879779057 | 2006 | 37.110181316822 | 2005 | 37.061877354767 | 2004 | 37.145639643927 | 2003 | 37.16021952062 | 2002 | 37.260367271077 | 2001 | 37.225178428316 | 2000 | 37.195859462263 | 1999 | 37.173715568412 | 1998 | 37.09825436113 | 1997 | 37.04184527414 | 1996 | 36.848594649441 | 1995 | 36.815353157673 | 1994 | 36.810563531186 | 1993 | 36.713621507347 | 1992 | 36.860025004078 | 1991 | 39.50432386716 | 1990 | 39.390856590227 | 1989 | 39.248356695328 | 1988 | 39.09497799207 | 1987 | 38.942098541209 | 1986 | 38.746454290065 | 1985 | 38.586913767386 | 1984 | 38.271500036869 | 1983 | 38.01518514859 | 1982 | 37.809310002493 | 1981 | 37.602436641897 | 1980 | 37.527989814201 | 1979 | 37.377360390378 | 1978 | 37.213737191201 | 1977 | 37.003856201722 | 1976 | 36.805469523027 | 1975 | 36.818637116854 | 1974 | 36.671214231949 | 1973 | 36.503897808307 | 1972 | 36.323716387642 | 1971 | 36.123725777474 | 1970 | 35.946071418719 | 1969 | 35.804479648424 | 1968 | 35.698993983668 | 1967 | 35.561416427977 | 1966 | 35.452752399846 | 1965 | 35.336110600157 | 1964 | 35.206444260495 | 1963 | 35.096896418039 | 1962 | 34.981571851986 | 1961 | 34.863197183417 |
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