Year | Value | 2022 | 49.872083981686 | 2021 | 49.875188190819 | 2020 | 49.879164029062 | 2019 | 49.881141249573 | 2018 | 49.879194280417 | 2017 | 49.87575714882 | 2016 | 49.872636143712 | 2015 | 49.868014337878 | 2014 | 49.862365203336 | 2013 | 49.85506399734 | 2012 | 49.847602804627 | 2011 | 49.839450527649 | 2010 | 49.825521054601 | 2009 | 49.810819405035 | 2008 | 49.795480876148 | 2007 | 49.77900585111 | 2006 | 49.761405308533 | 2005 | 49.741847239655 | 2004 | 49.722369363097 | 2003 | 49.701990396968 | 2002 | 49.679959742418 | 2001 | 49.654461469459 | 2000 | 49.628659365014 | 1999 | 49.611569526935 | 1998 | 49.601799825036 | 1997 | 49.592216789541 | 1996 | 49.590915943221 | 1995 | 49.599853752026 | 1994 | 49.613992350383 | 1993 | 49.608279634621 | 1992 | 49.581924087532 | 1991 | 49.558824578276 | 1990 | 49.536634405349 | 1989 | 49.51760999391 | 1988 | 49.502364317317 | 1987 | 49.489364318811 | 1986 | 49.479425598149 | 1985 | 49.472975127977 | 1984 | 49.466969688634 | 1983 | 49.52382258004 | 1982 | 49.624528485394 | 1981 | 49.684654661933 | 1980 | 49.737856256836 | 1979 | 49.813519398559 | 1978 | 49.896194918496 | 1977 | 49.976074999242 | 1976 | 49.999552764553 | 1975 | 49.983848927036 | 1974 | 49.996627677103 | 1973 | 50.019160135463 | 1972 | 50.037348045346 | 1971 | 50.030552610322 | 1970 | 50.040877261579 | 1969 | 50.100563682704 | 1968 | 50.180003877336 | 1967 | 50.271917796381 | 1966 | 50.371686672923 | 1965 | 50.478836382367 | 1964 | 50.597249075809 | 1963 | 50.724600954943 | 1962 | 50.858197394053 | 1961 | 50.999707554998 | 1960 | 51.114155951449 |
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