Year | Value | 2021 | 34.044378255436 | 2020 | 34.031858398595 | 2019 | 33.850654620085 | 2018 | 33.803336211476 | 2017 | 33.835115004005 | 2016 | 34.011254767963 | 2015 | 34.124791843528 | 2014 | 34.079646622664 | 2013 | 34.289847454576 | 2012 | 34.277931715695 | 2011 | 34.231295066292 | 2010 | 34.30058771238 | 2009 | 34.180756251237 | 2008 | 34.313311727217 | 2007 | 34.598796151027 | 2006 | 34.523536999427 | 2005 | 34.523721119468 | 2004 | 34.453169639324 | 2003 | 34.397755931338 | 2002 | 34.377481273408 | 2001 | 34.357420913862 | 2000 | 34.500218185952 | 1999 | 34.536638799426 | 1998 | 34.494925992328 | 1997 | 34.365480202694 | 1996 | 34.315615107816 | 1995 | 34.273129871149 | 1994 | 34.322081873414 | 1993 | 34.388871582232 | 1992 | 34.418809290509 | 1991 | 34.466876316292 | 1990 | 34.460062859276 | 1989 | 34.328021504694 | 1988 | 34.325853519023 | 1987 | 34.34132419573 | 1986 | 34.325645115789 | 1985 | 34.332293515039 | 1984 | 34.1963963 | 1983 | 33.997629075183 | 1982 | 33.716015805794 | 1981 | 33.567554914926 | 1980 | 33.391000601495 | 1979 | 33.058112368816 | 1978 | 32.735930188756 | 1977 | 32.400621949055 | 1976 | 32.031316177653 | 1975 | 31.708965836895 | 1974 | 31.437698461275 | 1973 | 31.190368289152 | 1972 | 30.938080416114 | 1971 | 30.63033537688 | 1970 | 30.318801114176 | 1969 | 30.081103849206 | 1968 | 29.949849822112 | 1967 | 29.750489928233 | 1966 | 29.601207877579 | 1965 | 29.432401032271 | 1964 | 29.250846593761 | 1963 | 29.037854398114 | 1962 | 28.858414357429 | 1961 | 28.656489365135 |
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