Year | Value | 2022 | 49.998405586824 | 2021 | 49.959072305594 | 2020 | 49.930860483734 | 2019 | 49.900589941658 | 2018 | 49.85964969878 | 2017 | 49.816822553568 | 2016 | 49.771601953887 | 2015 | 49.722642460918 | 2014 | 49.677889668735 | 2013 | 49.636153747488 | 2012 | 49.594519980675 | 2011 | 49.543152508745 | 2010 | 49.524285551434 | 2009 | 49.537744262642 | 2008 | 49.552801436725 | 2007 | 49.563660774222 | 2006 | 49.568421811367 | 2005 | 49.570990621655 | 2004 | 49.579056941451 | 2003 | 49.585249218319 | 2002 | 49.613327050475 | 2001 | 49.6553513193 | 2000 | 49.703067987192 | 1999 | 49.764563811164 | 1998 | 49.817325800377 | 1997 | 49.863096760746 | 1996 | 49.914159815348 | 1995 | 49.964443590236 | 1994 | 50.016477019404 | 1993 | 50.071936813052 | 1992 | 50.126682501979 | 1991 | 50.178431804968 | 1990 | 50.258967964704 | 1989 | 50.375917116827 | 1988 | 50.512129919801 | 1987 | 50.656567162696 | 1986 | 50.793414805784 | 1985 | 50.903794145721 | 1984 | 50.98375795539 | 1983 | 51.001762123512 | 1982 | 51.016222263658 | 1981 | 51.076431916994 | 1980 | 51.172525780805 | 1979 | 51.290397093719 | 1978 | 51.393890054378 | 1977 | 51.49435787769 | 1976 | 51.594837829739 | 1975 | 51.696598569444 | 1974 | 51.800508571897 | 1973 | 51.903234374681 | 1972 | 52.003054212268 | 1971 | 52.098239204344 | 1970 | 52.192440836488 | 1969 | 52.291992927507 | 1968 | 52.401671781618 | 1967 | 52.52432383281 | 1966 | 52.659790053905 | 1965 | 52.797629955409 | 1964 | 52.938645467305 | 1963 | 53.082099874074 | 1962 | 53.228459584392 | 1961 | 53.377639438042 | 1960 | 53.5170413343 |
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