Year | Value | 2022 | 48.245158031803 | 2021 | 48.207418233423 | 2020 | 48.137466505903 | 2019 | 48.037142834606 | 2018 | 47.976052061971 | 2017 | 47.972134654296 | 2016 | 48.025675401892 | 2015 | 48.156087331109 | 2014 | 48.320195440295 | 2013 | 48.450535160136 | 2012 | 48.531637446396 | 2011 | 48.585740821039 | 2010 | 48.611218423682 | 2009 | 48.663969478049 | 2008 | 48.829782458322 | 2007 | 49.090297787917 | 2006 | 49.389049515225 | 2005 | 49.633555659687 | 2004 | 49.748057271839 | 2003 | 49.800781525502 | 2002 | 49.848318944853 | 2001 | 49.887386843191 | 2000 | 49.925702832202 | 1999 | 49.960603080162 | 1998 | 49.990570099029 | 1997 | 50.015274859285 | 1996 | 50.030840152296 | 1995 | 50.040567184157 | 1994 | 50.050099419691 | 1993 | 50.059171183931 | 1992 | 50.064962776714 | 1991 | 50.067656672445 | 1990 | 50.077781516858 | 1989 | 50.094596996662 | 1988 | 50.107992447593 | 1987 | 50.11856884144 | 1986 | 50.127786301828 | 1985 | 50.144243758113 | 1984 | 50.1709714111 | 1983 | 50.198340599832 | 1982 | 50.225158745231 | 1981 | 50.25665488268 | 1980 | 50.300582678303 | 1979 | 50.363060870377 | 1978 | 50.430191056878 | 1977 | 50.491324266847 | 1976 | 50.553783725026 | 1975 | 50.619546219587 | 1974 | 50.680488689935 | 1973 | 50.741970391905 | 1972 | 50.811039070598 | 1971 | 50.878631631665 | 1970 | 50.942159697544 | 1969 | 50.994811640287 | 1968 | 51.040894459707 | 1967 | 51.089966823983 | 1966 | 51.126507167546 | 1965 | 51.149445467666 | 1964 | 51.177957798832 | 1963 | 51.214432682918 | 1962 | 51.257850268212 | 1961 | 51.30368382434 | 1960 | 51.350860381619 |
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