Year | Value | 2022 | 50.340954126963 | 2021 | 50.364889179035 | 2020 | 50.385507488297 | 2019 | 50.403225994532 | 2018 | 50.414625329176 | 2017 | 50.424607536933 | 2016 | 50.466851501117 | 2015 | 50.523827624463 | 2014 | 50.563882248582 | 2013 | 50.60789155586 | 2012 | 50.660701988985 | 2011 | 50.709343037312 | 2010 | 50.752956080811 | 2009 | 50.792556117762 | 2008 | 50.849666836338 | 2007 | 50.932828102824 | 2006 | 50.992359876442 | 2005 | 51.025915956726 | 2004 | 51.057131875503 | 2003 | 51.085710575306 | 2002 | 51.115168323145 | 2001 | 51.133027877874 | 2000 | 51.133289214138 | 1999 | 51.14579573403 | 1998 | 51.160719398004 | 1997 | 51.163158222988 | 1996 | 51.16053869964 | 1995 | 51.151635118552 | 1994 | 51.145613454436 | 1993 | 51.147118108234 | 1992 | 51.152938109134 | 1991 | 51.146607709076 | 1990 | 51.161353774674 | 1989 | 51.203603618785 | 1988 | 51.229827789071 | 1987 | 51.24474115713 | 1986 | 51.25697928878 | 1985 | 51.270992843082 | 1984 | 51.288879256826 | 1983 | 51.302198845727 | 1982 | 51.316251475524 | 1981 | 51.3386849674 | 1980 | 51.353314935182 | 1979 | 51.354233891404 | 1978 | 51.343383757386 | 1977 | 51.320739576588 | 1976 | 51.291971500176 | 1975 | 51.256076779347 | 1974 | 51.221918442469 | 1973 | 51.188080086109 | 1972 | 51.15886802319 | 1971 | 51.150939181564 | 1970 | 51.147288394359 | 1969 | 51.1538833193 | 1968 | 51.181568714565 | 1967 | 51.216404159047 | 1966 | 51.253890079396 | 1965 | 51.290676001063 | 1964 | 51.329868816307 | 1963 | 51.380763365642 | 1962 | 51.446508092527 | 1961 | 51.514515308732 | 1960 | 51.553758600582 |
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