Year | Value | 2021 | 24.134 | 2020 | 24.615 | 2019 | 25.118 | 2018 | 25.718 | 2017 | 26.408 | 2016 | 27.105 | 2015 | 27.737 | 2014 | 28.423 | 2013 | 29.019 | 2012 | 29.294 | 2011 | 29.665 | 2010 | 30.083 | 2009 | 31.001 | 2008 | 31.376 | 2007 | 31.247 | 2006 | 31.229 | 2005 | 31.59 | 2004 | 31.63 | 2003 | 31.443 | 2002 | 31.395 | 2001 | 31.806 | 2000 | 32.162 | 1999 | 32.374 | 1998 | 32.146 | 1997 | 32.583 | 1996 | 33.39 | 1995 | 34.166 | 1994 | 36.522 | 1993 | 37.768 | 1992 | 38.719 | 1991 | 39.48 | 1990 | 40.23 | 1989 | 41.674 | 1988 | 42.264 | 1987 | 43.443 | 1986 | 44.507 | 1985 | 45.827 | 1984 | 46.587 | 1983 | 47.059 | 1982 | 47.576 | 1981 | 48.083 | 1980 | 48.578 | 1979 | 48.87 | 1978 | 49.238 | 1977 | 49.617 | 1976 | 49.871 | 1975 | 49.837 | 1974 | 49.719 | 1973 | 49.032 | 1972 | 49.065 | 1971 | 49.107 | 1970 | 48.753 | 1969 | 48.397 | 1968 | 48.005 | 1967 | 47.576 | 1966 | 47.812 | 1965 | 47.691 | 1964 | 47.599 | 1963 | 47.85 | 1962 | 47.508 | 1961 | 47.496 | 1960 | 47.526 |
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