Year | Value | 2022 | 49.997266694204 | 2021 | 49.979557678258 | 2020 | 49.961065537505 | 2019 | 49.947171102309 | 2018 | 49.937902961523 | 2017 | 49.929798443041 | 2016 | 49.922783394133 | 2015 | 49.915834807267 | 2014 | 49.908133449119 | 2013 | 49.899281863199 | 2012 | 49.88867766645 | 2011 | 49.875998800653 | 2010 | 49.861754153378 | 2009 | 49.846895901856 | 2008 | 49.832430972547 | 2007 | 49.819268717286 | 2006 | 49.808123499179 | 2005 | 49.798782044534 | 2004 | 49.790692289454 | 2003 | 49.783065669938 | 2002 | 49.775423823851 | 2001 | 49.767332761847 | 2000 | 49.758422723422 | 1999 | 49.748803990323 | 1998 | 49.738716203547 | 1997 | 49.727828084379 | 1996 | 49.716121266876 | 1995 | 49.703155334533 | 1994 | 49.688376540786 | 1993 | 49.671620200046 | 1992 | 49.652518691409 | 1991 | 49.631421349904 | 1990 | 49.609178568863 | 1989 | 49.580890001605 | 1988 | 49.553224031985 | 1987 | 49.532937697602 | 1986 | 49.513965535657 | 1985 | 49.49607772187 | 1984 | 49.479250336542 | 1983 | 49.463592787035 | 1982 | 49.448432310839 | 1981 | 49.433475846342 | 1980 | 49.41872378304 | 1979 | 49.404073827266 | 1978 | 49.389738088901 | 1977 | 49.376078492891 | 1976 | 49.3631104918 | 1975 | 49.35084697696 | 1974 | 49.339021787735 | 1973 | 49.327636677234 | 1972 | 49.317191694236 | 1971 | 49.307151946799 | 1970 | 49.297778375769 | 1969 | 49.28929791413 | 1968 | 49.280121207467 | 1967 | 49.268405948794 | 1966 | 49.253662820575 | 1965 | 49.235820521977 | 1964 | 49.215430123299 | 1963 | 49.193726905853 | 1962 | 49.170727140348 | 1961 | 49.146904978498 | 1960 | 49.122928440295 |
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