Year | Value | 2021 | 10.649722141176 | 2020 | 10.628524458335 | 2019 | 10.611030031433 | 2018 | 10.577269142621 | 2017 | 10.503955529627 | 2016 | 10.422333355098 | 2015 | 10.339555150956 | 2014 | 10.293573957073 | 2013 | 10.218627525469 | 2012 | 10.090606280551 | 2011 | 9.9145637983275 | 2010 | 9.7665262459093 | 2009 | 9.6570205563695 | 2008 | 9.5057130909581 | 2007 | 9.5201232436738 | 2006 | 9.3834500095784 | 2005 | 9.3159337051535 | 2004 | 9.1752698825525 | 2003 | 9.1856076474973 | 2002 | 8.9891312469066 | 2001 | 8.9326283525747 | 2000 | 8.875098421223 | 1999 | 8.8746717232553 | 1998 | 8.8381362800971 | 1997 | 8.8163109760402 | 1996 | 8.7945853254996 | 1995 | 8.678908389755 | 1994 | 8.4748999117752 | 1993 | 8.4444911436133 | 1992 | 8.2951297638292 | 1991 | 6.7529332355635 | 1990 | 6.6301089514173 | 1989 | 6.5353406464066 | 1988 | 6.5517644323126 | 1987 | 6.5276898144627 | 1986 | 6.5430424838967 | 1985 | 6.5282508754719 | 1984 | 6.5073896070385 | 1983 | 6.518304793945 | 1982 | 6.520396021343 | 1981 | 6.503462179974 | 1980 | 6.5211611045373 | 1979 | 6.4977495587893 | 1978 | 6.456843110663 | 1977 | 6.4333295538224 | 1976 | 6.4156816348053 | 1975 | 6.3717658594478 | 1974 | 6.3715338549292 | 1973 | 6.3857868439724 | 1972 | 6.4132777116744 | 1971 | 6.3808905113204 | 1970 | 6.3457491238497 | 1969 | 6.369210717807 | 1968 | 6.3151470447751 | 1967 | 6.2637865553948 | 1966 | 6.2314503585059 | 1965 | 6.2280841298077 | 1964 | 6.1906475864064 | 1963 | 6.1589744345641 | 1962 | 6.1179676486041 | 1961 | 6.0639039755722 |
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