| Year | Value | | 2021 | 10.941412204996 | | 2020 | 10.92449305859 | | 2019 | 10.883544333456 | | 2018 | 10.910525277392 | | 2017 | 10.926630709972 | | 2016 | 10.938246800841 | | 2015 | 10.942600144196 | | 2014 | 10.913375769037 | | 2013 | 10.925113371866 | | 2012 | 10.933379755262 | | 2011 | 10.936928439196 | | 2010 | 10.934274780558 | | 2009 | 10.920642426586 | | 2008 | 10.920572630458 | | 2007 | 10.94933271094 | | 2006 | 10.945500600014 | | 2005 | 10.907832571437 | | 2004 | 10.893488896406 | | 2003 | 10.874458441789 | | 2002 | 10.844764247359 | | 2001 | 10.841536577295 | | 2000 | 10.841351402163 | | 1999 | 10.885469680848 | | 1998 | 10.892816122856 | | 1997 | 10.897276427753 | | 1996 | 10.87030635461 | | 1995 | 10.90928109261 | | 1994 | 10.951352767895 | | 1993 | 11.007992947443 | | 1992 | 11.069939306825 | | 1991 | 11.391762032923 | | 1990 | 11.387115099668 | | 1989 | 11.383277573582 | | 1988 | 11.376895355565 | | 1987 | 11.383002207795 | | 1986 | 11.358088177847 | | 1985 | 11.341301746597 | | 1984 | 11.143203030845 | | 1983 | 10.938825134816 | | 1982 | 10.811790153439 | | 1981 | 10.688807637817 | | 1980 | 10.633865720812 | | 1979 | 10.640168795815 | | 1978 | 10.552070830464 | | 1977 | 10.475633662173 | | 1976 | 10.403305363112 | | 1975 | 10.330982985419 | | 1974 | 10.323845220423 | | 1973 | 10.272913777606 | | 1972 | 10.204230961915 | | 1971 | 10.120829162303 | | 1970 | 10.101320007878 | | 1969 | 10.108813164006 | | 1968 | 10.083685687238 | | 1967 | 10.036074954948 | | 1966 | 9.9973354992184 | | 1965 | 9.9551828334359 | | 1964 | 9.9220688756822 | | 1963 | 9.889317088138 | | 1962 | 9.8373750632486 | | 1961 | 9.7999379851466 |
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