| Year | Value | | 2022 | 46.968478812242 | | 2021 | 46.928625077198 | | 2020 | 46.84659289351 | | 2019 | 46.747848342783 | | 2018 | 46.633703367861 | | 2017 | 46.513074764585 | | 2016 | 46.400297511004 | | 2015 | 46.297226669456 | | 2014 | 46.201626951174 | | 2013 | 46.12004072401 | | 2012 | 46.050668208339 | | 2011 | 45.995093873859 | | 2010 | 45.95741535811 | | 2009 | 45.940595740453 | | 2008 | 45.947776594432 | | 2007 | 45.99204624837 | | 2006 | 46.056464592113 | | 2005 | 46.121291832628 | | 2004 | 46.186003527737 | | 2003 | 46.250181933466 | | 2002 | 46.319712816347 | | 2001 | 46.395003345372 | | 2000 | 46.467796613936 | | 1999 | 46.532114969301 | | 1998 | 46.588005489004 | | 1997 | 46.638741658764 | | 1996 | 46.696473046102 | | 1995 | 46.762000145706 | | 1994 | 46.835608212906 | | 1993 | 46.909617666809 | | 1992 | 46.968208060506 | | 1991 | 47.00983939316 | | 1990 | 47.033860586548 | | 1989 | 47.044402864427 | | 1988 | 47.043581736959 | | 1987 | 47.032037738427 | | 1986 | 47.013471865288 | | 1985 | 47.003309689582 | | 1984 | 47.007755835401 | | 1983 | 47.014399441959 | | 1982 | 47.026062429747 | | 1981 | 47.043730543447 | | 1980 | 47.061802121205 | | 1979 | 47.081512685912 | | 1978 | 47.100408021269 | | 1977 | 47.112881055008 | | 1976 | 47.122627368292 | | 1975 | 47.12968342662 | | 1974 | 47.128873591581 | | 1973 | 47.120733578767 | | 1972 | 47.107432971522 | | 1971 | 47.086283305202 | | 1970 | 47.052487004489 | | 1969 | 47.002173806326 | | 1968 | 46.939245118467 | | 1967 | 46.875768410226 | | 1966 | 46.810561620259 | | 1965 | 46.738022108898 | | 1964 | 46.662442140378 | | 1963 | 46.585569205734 | | 1962 | 46.501444049557 | | 1961 | 46.413463180806 | | 1960 | 46.32842134254 |
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