Year | Value | 2021 | 37.949692264899 | 2020 | 38.027106302944 | 2019 | 38.105034139778 | 2018 | 38.182405150339 | 2017 | 38.259884995126 | 2016 | 38.338660726511 | 2015 | 38.420568546425 | 2014 | 38.502806407833 | 2013 | 38.585375856322 | 2012 | 38.667655833813 | 2011 | 38.750211135043 | 2010 | 38.832838878629 | 2009 | 38.915451463265 | 2008 | 38.999110248911 | 2007 | 39.083077776501 | 2006 | 39.15905218221 | 2005 | 39.234877637662 | 2004 | 39.311924123808 | 2003 | 39.389477968792 | 2002 | 39.465603458443 | 2001 | 39.540771350699 | 2000 | 39.617273040112 | 1999 | 39.693764421325 | 1998 | 39.774923955787 | 1997 | 39.851510491361 | 1996 | 39.928465201295 | 1995 | 40.022013844285 | 1994 | 40.140823620989 | 1993 | 40.259988044375 | 1992 | 40.379504586836 | 1991 | 40.499375780275 | 1990 | 40.60359070633 | 1989 | 40.740187188252 | 1988 | 40.8611299369 | 1987 | 40.982432404742 | 1986 | 41.104094593962 | 1985 | 41.211711845039 | 1984 | 41.348500675078 | 1983 | 41.471249630964 | 1982 | 41.593550611695 | 1981 | 41.716215884606 | 1980 | 41.826727965572 | 1979 | 41.962631717554 | 1978 | 41.613539769278 | 1977 | 41.524994940295 | 1976 | 41.555353167375 | 1975 | 41.585711394455 | 1974 | 41.67931592795 | 1973 | 41.836166767861 | 1972 | 42.066383323214 | 1971 | 42.132159481886 | 1970 | 42.3471969237 | 1969 | 42.688726978344 | 1968 | 42.655838899008 | 1967 | 42.724144909937 | 1966 | 42.898704715645 | 1965 | 43.047965998786 | 1964 | 43.270592997369 | 1963 | 43.493219995952 | 1962 | 43.852459016393 | 1961 | 43.925824731836 |
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