| Year | Value | | 2022 | 47.098555188477 | | 2021 | 47.051393851465 | | 2020 | 47.002741726278 | | 2019 | 46.954430138939 | | 2018 | 46.905770401629 | | 2017 | 46.855199101731 | | 2016 | 46.831857085124 | | 2015 | 46.831720200088 | | 2014 | 46.823891128895 | | 2013 | 46.812340424948 | | 2012 | 46.800296750307 | | 2011 | 46.787816595662 | | 2010 | 46.773992368706 | | 2009 | 46.756956647623 | | 2008 | 46.735929781931 | | 2007 | 46.709721337883 | | 2006 | 46.678697679945 | | 2005 | 46.698968677402 | | 2004 | 46.854187211823 | | 2003 | 47.101053059514 | | 2002 | 47.361270854603 | | 2001 | 47.633090972989 | | 2000 | 47.917003714193 | | 1999 | 48.212928422564 | | 1998 | 48.34880811569 | | 1997 | 48.306803324404 | | 1996 | 48.256166580464 | | 1995 | 48.203724485154 | | 1994 | 48.148716571385 | | 1993 | 48.090577108429 | | 1992 | 48.025438506514 | | 1991 | 47.960930756901 | | 1990 | 47.895573756988 | | 1989 | 47.842281182413 | | 1988 | 47.804843011354 | | 1987 | 47.77131896052 | | 1986 | 47.740663646872 | | 1985 | 47.713238450616 | | 1984 | 47.68921548818 | | 1983 | 47.667164437661 | | 1982 | 47.645753854017 | | 1981 | 47.627268506746 | | 1980 | 47.615573006596 | | 1979 | 47.61293628113 | | 1978 | 47.618435662294 | | 1977 | 47.630231649871 | | 1976 | 47.647060439032 | | 1975 | 47.668685010603 | | 1974 | 47.693065995388 | | 1973 | 47.721952698605 | | 1972 | 47.755446090597 | | 1971 | 47.792524859392 | | 1970 | 47.832007333704 | | 1969 | 47.87691499364 | | 1968 | 47.925398604794 | | 1967 | 47.973936662256 | | 1966 | 48.024534558287 | | 1965 | 48.076546017803 | | 1964 | 48.128465430562 | | 1963 | 48.182446268334 | | 1962 | 48.240702262474 | | 1961 | 48.288861193195 | | 1960 | 48.323737040485 |
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