Year | Value | 2022 | 39.553702787286 | 2021 | 39.312288467754 | 2020 | 39.094823592937 | 2019 | 38.882794446526 | 2018 | 38.677022727037 | 2017 | 38.468544780082 | 2016 | 38.259760265423 | 2015 | 38.044097757036 | 2014 | 37.82249269158 | 2013 | 37.597847895963 | 2012 | 37.370794848661 | 2011 | 37.139835449821 | 2010 | 36.898289799127 | 2009 | 36.63267762172 | 2008 | 36.344373397184 | 2007 | 36.05718209335 | 2006 | 35.801960805896 | 2005 | 35.560324091196 | 2004 | 35.33865798317 | 2003 | 35.117246914524 | 2002 | 34.912121716098 | 2001 | 34.704440706853 | 2000 | 34.459670914568 | 1999 | 34.208315428434 | 1998 | 33.98527051898 | 1997 | 33.765676113935 | 1996 | 33.53271568204 | 1995 | 33.201117528917 | 1994 | 32.911647066687 | 1993 | 32.598801599566 | 1992 | 32.276614243104 | 1991 | 31.943032225451 | 1990 | 31.586910893386 | 1989 | 31.209433596309 | 1988 | 30.810598459977 | 1987 | 30.394832869117 | 1986 | 29.992854163227 | 1985 | 29.764592947961 | 1984 | 29.533227153609 | 1983 | 29.299068883132 | 1982 | 29.0752519675 | 1981 | 28.86528157553 | 1980 | 28.66605661367 | 1979 | 28.497410462427 | 1978 | 28.338115237685 | 1977 | 28.181252208426 | 1976 | 28.018461352285 | 1975 | 27.809211921372 | 1974 | 27.619224274526 | 1973 | 27.401693887857 | 1972 | 27.094765379707 | 1971 | 26.77173147706 | 1970 | 26.424962017953 | 1969 | 26.037904579558 | 1968 | 25.63686304929 | 1967 | 25.256950819315 | 1966 | 24.881300334703 | 1965 | 24.417155096477 | 1964 | 23.947879842261 | 1963 | 23.481303648888 | 1962 | 23.023292208969 | 1961 | 22.57700730172 | 1960 | 22.143263494479 |
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