Year | Value | 2022 | 51.153375508867 | 2021 | 51.176406870428 | 2020 | 51.198106909052 | 2019 | 51.220089794201 | 2018 | 51.243319705544 | 2017 | 51.266777240337 | 2016 | 51.292956465943 | 2015 | 51.322918575353 | 2014 | 51.346431811705 | 2013 | 51.36353866236 | 2012 | 51.382482324151 | 2011 | 51.402341147292 | 2010 | 51.422964672519 | 2009 | 51.444745596871 | 2008 | 51.470512364603 | 2007 | 51.495988830106 | 2006 | 51.518970469043 | 2005 | 51.539429967928 | 2004 | 51.554730543151 | 2003 | 51.567524177933 | 2002 | 51.578783451597 | 2001 | 51.587255204882 | 2000 | 51.59149175369 | 1999 | 51.592802775152 | 1998 | 51.593106283416 | 1997 | 51.592693159246 | 1996 | 51.591182032307 | 1995 | 51.58962611509 | 1994 | 51.589544701685 | 1993 | 51.592218597285 | 1992 | 51.598851430905 | 1991 | 51.607583626076 | 1990 | 51.617359461198 | 1989 | 51.629636339016 | 1988 | 51.64373216923 | 1987 | 51.657880071004 | 1986 | 51.671968604255 | 1985 | 51.68734340654 | 1984 | 51.703683658957 | 1983 | 51.718930039596 | 1982 | 51.733167121619 | 1981 | 51.746315220487 | 1980 | 51.75915971573 | 1979 | 51.772306926989 | 1978 | 51.783269495348 | 1977 | 51.79080925829 | 1976 | 51.795873145744 | 1975 | 51.799183151109 | 1974 | 51.798132923608 | 1973 | 51.793783265135 | 1972 | 51.789593970246 | 1971 | 51.806811383477 | 1970 | 51.824324567714 | 1969 | 51.821636486669 | 1968 | 51.821237840578 | 1967 | 51.821671437303 | 1966 | 51.822261966674 | 1965 | 51.822509328027 | 1964 | 51.822417237192 | 1963 | 51.82172671939 | 1962 | 51.820916058327 | 1961 | 51.820211007193 | 1960 | 51.819417676174 |
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