Year | Value | 2022 | 51.754839943744 | 2021 | 51.792570222842 | 2020 | 51.86253829752 | 2019 | 51.962843020027 | 2018 | 52.023950320809 | 2017 | 52.027853272311 | 2016 | 51.974327052851 | 2015 | 51.843899939249 | 2014 | 51.679794293386 | 2013 | 51.549451644827 | 2012 | 51.468367805071 | 2011 | 51.414262179404 | 2010 | 51.388787151725 | 2009 | 51.336019131357 | 2008 | 51.170208749007 | 2007 | 50.909708238004 | 2006 | 50.610935613506 | 2005 | 50.366447336382 | 2004 | 50.251949085089 | 2003 | 50.199221588312 | 2002 | 50.151668190712 | 2001 | 50.11261300466 | 2000 | 50.074283710153 | 1999 | 50.039393455018 | 1998 | 50.009426589188 | 1997 | 49.984690270643 | 1996 | 49.969177582283 | 1995 | 49.959407640654 | 1994 | 49.949936861166 | 1993 | 49.940839992157 | 1992 | 49.93504466495 | 1991 | 49.932320491954 | 1990 | 49.922226287028 | 1989 | 49.90538707593 | 1988 | 49.891979045243 | 1987 | 49.881435177487 | 1986 | 49.872201020521 | 1985 | 49.855769350124 | 1984 | 49.829010970187 | 1983 | 49.801641566835 | 1982 | 49.774845691626 | 1981 | 49.743349752593 | 1980 | 49.699407919614 | 1979 | 49.636919837999 | 1978 | 49.569779061209 | 1977 | 49.508650368218 | 1976 | 49.446252361098 | 1975 | 49.38046973798 | 1974 | 49.31950074335 | 1973 | 49.258035141252 | 1972 | 49.18893861259 | 1971 | 49.121373916843 | 1970 | 49.05780549975 | 1969 | 49.005206105374 | 1968 | 48.95909945072 | 1967 | 48.910033064669 | 1966 | 48.873505031248 | 1965 | 48.850503280314 | 1964 | 48.822015986564 | 1963 | 48.785587232506 | 1962 | 48.742197149481 | 1961 | 48.696315932005 | 1960 | 48.649188930472 |
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