Year | Value | 2021 | 28.263 | 2020 | 28.435 | 2019 | 28.917 | 2018 | 29.535 | 2017 | 30.41 | 2016 | 31.602 | 2015 | 32.754 | 2014 | 34.032 | 2013 | 35.159 | 2012 | 36.148 | 2011 | 36.628 | 2010 | 36.873 | 2009 | 37.336 | 2008 | 37.81 | 2007 | 38.241 | 2006 | 38.672 | 2005 | 39.075 | 2004 | 39.396 | 2003 | 39.633 | 2002 | 39.85 | 2001 | 39.941 | 2000 | 39.438 | 1999 | 39.035 | 1998 | 38.761 | 1997 | 38.592 | 1996 | 38.716 | 1995 | 38.876 | 1994 | 39.125 | 1993 | 39.409 | 1992 | 39.669 | 1991 | 39.943 | 1990 | 40.119 | 1989 | 40.201 | 1988 | 40.224 | 1987 | 40.245 | 1986 | 40.333 | 1985 | 40.237 | 1984 | 40.19 | 1983 | 40.213 | 1982 | 40.19 | 1981 | 40.555 | 1980 | 40.637 | 1979 | 40.537 | 1978 | 40.458 | 1977 | 39.961 | 1976 | 39.515 | 1975 | 38.915 | 1974 | 38.522 | 1973 | 38.61 | 1972 | 38.639 | 1971 | 38.538 | 1970 | 38.167 | 1969 | 37.687 | 1968 | 37.418 | 1967 | 37.469 | 1966 | 37.938 | 1965 | 38.872 | 1964 | 40.255 | 1963 | 42.033 | 1962 | 44.139 | 1961 | 46.413 | 1960 | 46.014 |
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