Year | Value | 2022 | 31.46 | 2021 | 31.579 | 2020 | 31.685 | 2019 | 31.778 | 2018 | 31.858 | 2017 | 31.925 | 2016 | 31.979 | 2015 | 32.02 | 2014 | 32.048 | 2013 | 32.075 | 2012 | 32.103 | 2011 | 32.131 | 2010 | 32.159 | 2009 | 32.186 | 2008 | 32.166 | 2007 | 32.1 | 2006 | 32.033 | 2005 | 32 | 2004 | 32.1 | 2003 | 32.2 | 2002 | 32.15 | 2001 | 32.05 | 2000 | 31.933 | 1999 | 31.78 | 1998 | 31.549 | 1997 | 31.4 | 1996 | 31.35 | 1995 | 31.25 | 1994 | 31.099 | 1993 | 31.201 | 1992 | 31.148 | 1991 | 30.799 | 1990 | 30.75 | 1989 | 30.8 | 1988 | 30.888 | 1987 | 31.053 | 1986 | 31.218 | 1985 | 31.44 | 1984 | 31.717 | 1983 | 31.997 | 1982 | 32.278 | 1981 | 32.56 | 1980 | 32.905 | 1979 | 33.314 | 1978 | 33.857 | 1977 | 34.513 | 1976 | 35.174 | 1975 | 35.843 | 1974 | 36.516 | 1973 | 37.195 | 1972 | 37.878 | 1971 | 38.567 | 1970 | 39.287 | 1969 | 40.054 | 1968 | 40.825 | 1967 | 41.602 | 1966 | 42.383 | 1965 | 43.168 | 1964 | 43.955 | 1963 | 44.747 | 1962 | 45.541 | 1961 | 46.337 | 1960 | 47.133 |
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