Year | Value | 2021 | 17.103 | 2020 | 17.363 | 2019 | 17.663 | 2018 | 17.869 | 2017 | 18.129 | 2016 | 18.33 | 2015 | 18.402 | 2014 | 18.404 | 2013 | 18.573 | 2012 | 18.762 | 2011 | 19.104 | 2010 | 19.409 | 2009 | 19.813 | 2008 | 20.151 | 2007 | 20.592 | 2006 | 20.837 | 2005 | 21.25 | 2004 | 21.784 | 2003 | 22.421 | 2002 | 23.012 | 2001 | 22.978 | 2000 | 22.942 | 1999 | 23.198 | 1998 | 23.603 | 1997 | 24.075 | 1996 | 24.583 | 1995 | 24.984 | 1994 | 25.534 | 1993 | 26.108 | 1992 | 26.56 | 1991 | 27.038 | 1990 | 27.478 | 1989 | 27.886 | 1988 | 28.149 | 1987 | 29.089 | 1986 | 30.154 | 1985 | 31.261 | 1984 | 32.33 | 1983 | 32.803 | 1982 | 32.921 | 1981 | 33.061 | 1980 | 33.501 | 1979 | 34.006 | 1978 | 34.314 | 1977 | 34.714 | 1976 | 35.111 | 1975 | 35.479 | 1974 | 35.909 | 1973 | 36.508 | 1972 | 36.989 | 1971 | 37.456 | 1970 | 37.846 | 1969 | 38.231 | 1968 | 38.688 | 1967 | 39.144 | 1966 | 39.573 | 1965 | 40.107 | 1964 | 40.445 | 1963 | 40.856 | 1962 | 41.325 | 1961 | 41.719 | 1960 | 42.21 |
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