Year | Value | 2022 | 49.941981048414 | 2021 | 49.937625957961 | 2020 | 49.932185746076 | 2019 | 49.924898635801 | 2018 | 49.916688797076 | 2017 | 49.906733192705 | 2016 | 49.893577412345 | 2015 | 49.878696878506 | 2014 | 49.865845700407 | 2013 | 49.854921587444 | 2012 | 49.843838630678 | 2011 | 49.833048844731 | 2010 | 49.821527976802 | 2009 | 49.81056670342 | 2008 | 49.800184545024 | 2007 | 49.789131653224 | 2006 | 49.778677308332 | 2005 | 49.769435242473 | 2004 | 49.760407865462 | 2003 | 49.750285796171 | 2002 | 49.73870905597 | 2001 | 49.729637885254 | 2000 | 49.723420938788 | 1999 | 49.719348434239 | 1998 | 49.720411231393 | 1997 | 49.721822960441 | 1996 | 49.725363230008 | 1995 | 49.728640127715 | 1994 | 49.720327560342 | 1993 | 49.710086065729 | 1992 | 49.707415948864 | 1991 | 49.706556628856 | 1990 | 49.70547516042 | 1989 | 49.703314483216 | 1988 | 49.708115712133 | 1987 | 49.713407582782 | 1986 | 49.711949610224 | 1985 | 49.710756943285 | 1984 | 49.713727944145 | 1983 | 49.720609389652 | 1982 | 49.727417764773 | 1981 | 49.73633519743 | 1980 | 49.744197814569 | 1979 | 49.746684106526 | 1978 | 49.745020609502 | 1977 | 49.740975928964 | 1976 | 49.733781669409 | 1975 | 49.7237478236 | 1974 | 49.71199027835 | 1973 | 49.701958830757 | 1972 | 49.696574098718 | 1971 | 49.692677718968 | 1970 | 49.688611685217 | 1969 | 49.685514945953 | 1968 | 49.681764371507 | 1967 | 49.678424959258 | 1966 | 49.673169765839 | 1965 | 49.665810068069 | 1964 | 49.659543433309 | 1963 | 49.65379226536 | 1962 | 49.647475852408 | 1961 | 49.644349362526 | 1960 | 49.644649507032 |
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