Year | Value | 2021 | 41.989058891641 | 2020 | 41.949740605972 | 2019 | 41.876470614135 | 2018 | 41.818128833884 | 2017 | 41.709459838522 | 2016 | 41.572896559244 | 2015 | 41.424862312065 | 2014 | 41.334978437589 | 2013 | 41.207623146525 | 2012 | 41.013022267303 | 2011 | 40.985282553679 | 2010 | 40.783222477167 | 2009 | 40.548845226608 | 2008 | 40.319589472643 | 2007 | 40.264026599187 | 2006 | 40.089084134084 | 2005 | 39.904999176062 | 2004 | 39.419279144882 | 2003 | 39.724893734344 | 2002 | 39.326782331878 | 2001 | 39.206973218518 | 2000 | 38.976891570861 | 1999 | 38.771402797414 | 1998 | 38.586669900511 | 1997 | 38.453466570481 | 1996 | 38.247640730959 | 1995 | 38.067488339504 | 1994 | 37.861372988003 | 1993 | 37.626153673937 | 1992 | 38.592363580833 | 1991 | 38.44373801992 | 1990 | 38.339257210851 | 1989 | 38.210525333853 | 1988 | 38.081586159147 | 1987 | 37.839946130235 | 1986 | 37.725725092835 | 1985 | 37.464115384669 | 1984 | 37.308987599451 | 1983 | 37.313962744456 | 1982 | 37.256817676137 | 1981 | 37.235949706812 | 1980 | 37.247489279254 | 1979 | 37.186405554473 | 1978 | 37.168785249248 | 1977 | 37.139210776164 | 1976 | 37.12138317323 | 1975 | 37.068335689617 | 1974 | 37.043472582872 | 1973 | 37.077611426724 | 1972 | 37.041598895579 | 1971 | 36.948043701469 | 1970 | 36.913495993157 | 1969 | 36.961240926044 | 1968 | 36.898571383166 | 1967 | 36.82560662321 | 1966 | 36.800732273225 | 1965 | 36.819042558631 | 1964 | 36.803081517391 | 1963 | 36.754300153254 | 1962 | 36.707107983699 | 1961 | 36.643954772904 |
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