Year | Value | 2022 | 50.771603506513 | 2021 | 50.773584253837 | 2020 | 50.794040634557 | 2019 | 50.828738323527 | 2018 | 50.877246128015 | 2017 | 50.92994909633 | 2016 | 50.988915209656 | 2015 | 51.056798410135 | 2014 | 51.128597943248 | 2013 | 51.192254224465 | 2012 | 51.215962229212 | 2011 | 51.213232092184 | 2010 | 51.214377626547 | 2009 | 51.213616143382 | 2008 | 51.213929530719 | 2007 | 51.217527687982 | 2006 | 51.214562727355 | 2005 | 51.203051464024 | 2004 | 51.193861245613 | 2003 | 51.18918235452 | 2002 | 51.20104992128 | 2001 | 51.215418986529 | 2000 | 51.220309378253 | 1999 | 51.230841022929 | 1998 | 51.253408517351 | 1997 | 51.291285919973 | 1996 | 51.350661800099 | 1995 | 51.406162387312 | 1994 | 51.339967520127 | 1993 | 51.068316078622 | 1992 | 50.669897304086 | 1991 | 50.462310428293 | 1990 | 50.439756047091 | 1989 | 50.426690886208 | 1988 | 50.421905666634 | 1987 | 50.423439857667 | 1986 | 50.428107837677 | 1985 | 50.438299311068 | 1984 | 50.455432997586 | 1983 | 50.472658567924 | 1982 | 50.496243226214 | 1981 | 50.533006607695 | 1980 | 50.581477301408 | 1979 | 50.640893758293 | 1978 | 50.710380027114 | 1977 | 50.786155845601 | 1976 | 50.866506454741 | 1975 | 50.950252232048 | 1974 | 51.036425986734 | 1973 | 51.122858058731 | 1972 | 51.205632135155 | 1971 | 51.281624733562 | 1970 | 51.349355966265 | 1969 | 51.409514594831 | 1968 | 51.462759063965 | 1967 | 51.509255677421 | 1966 | 51.549429429396 | 1965 | 51.581664033575 | 1964 | 51.607159604773 | 1963 | 51.629185984065 | 1962 | 51.649529212 | 1961 | 51.668930600334 | 1960 | 51.687719288566 |
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