| Year | Value | | 2022 | 46.043913793396 | | 2021 | 46.094466717901 | | 2020 | 46.140066059495 | | 2019 | 46.182606914989 | | 2018 | 46.210043881878 | | 2017 | 46.223664167115 | | 2016 | 46.23074934256 | | 2015 | 46.231726276154 | | 2014 | 46.234750079407 | | 2013 | 46.240559802219 | | 2012 | 46.251661766774 | | 2011 | 46.283865189393 | | 2010 | 46.326730910071 | | 2009 | 46.359616418118 | | 2008 | 46.38445759048 | | 2007 | 46.403546677148 | | 2006 | 46.424144530973 | | 2005 | 46.454054150898 | | 2004 | 46.48441875126 | | 2003 | 46.512624134725 | | 2002 | 46.541730814844 | | 2001 | 46.564265078776 | | 2000 | 46.583356107547 | | 1999 | 46.608896942391 | | 1998 | 46.640722740485 | | 1997 | 46.677833623244 | | 1996 | 46.717722936486 | | 1995 | 46.758995864533 | | 1994 | 46.797595699255 | | 1993 | 46.814288347752 | | 1992 | 46.803756467101 | | 1991 | 46.785295349791 | | 1990 | 46.760390371601 | | 1989 | 46.718330780613 | | 1988 | 46.672514970755 | | 1987 | 46.627975030497 | | 1986 | 46.575423435575 | | 1985 | 46.535762454764 | | 1984 | 46.520455294578 | | 1983 | 46.510188024869 | | 1982 | 46.501892406739 | | 1981 | 46.496271534995 | | 1980 | 46.487038079985 | | 1979 | 46.482776985579 | | 1978 | 46.477046657718 | | 1977 | 46.462291804598 | | 1976 | 46.44083979542 | | 1975 | 46.411573500922 | | 1974 | 46.37333831306 | | 1973 | 46.320590455873 | | 1972 | 46.256908363553 | | 1971 | 46.180448871391 | | 1970 | 46.092297868471 | | 1969 | 45.99607551273 | | 1968 | 45.883557783819 | | 1967 | 45.759039957836 | | 1966 | 45.627976698862 | | 1965 | 45.48955065702 | | 1964 | 45.345821017105 | | 1963 | 45.190297028655 | | 1962 | 45.028366162748 | | 1961 | 44.867454841517 | | 1960 | 44.710718552689 |
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