Year | Value | 2021 | 17.692 | 2020 | 17.919 | 2019 | 18.228 | 2018 | 18.814 | 2017 | 19.317 | 2016 | 19.701 | 2015 | 20.111 | 2014 | 20.461 | 2013 | 20.759 | 2012 | 21.129 | 2011 | 21.213 | 2010 | 21.165 | 2009 | 21.399 | 2008 | 21.659 | 2007 | 21.792 | 2006 | 21.968 | 2005 | 22.333 | 2004 | 22.69 | 2003 | 22.688 | 2002 | 22.951 | 2001 | 23.259 | 2000 | 23.538 | 1999 | 23.856 | 1998 | 24.136 | 1997 | 24.392 | 1996 | 24.649 | 1995 | 24.898 | 1994 | 25.172 | 1993 | 25.492 | 1992 | 25.849 | 1991 | 26.23 | 1990 | 27.031 | 1989 | 27.46 | 1988 | 27.779 | 1987 | 28.196 | 1986 | 28.665 | 1985 | 29.066 | 1984 | 29.577 | 1983 | 30.019 | 1982 | 30.127 | 1981 | 30.319 | 1980 | 30.485 | 1979 | 30.763 | 1978 | 31.166 | 1977 | 31.772 | 1976 | 32.469 | 1975 | 33.286 | 1974 | 34.114 | 1973 | 34.952 | 1972 | 35.899 | 1971 | 36.644 | 1970 | 37.279 | 1969 | 38.013 | 1968 | 38.726 | 1967 | 39.404 | 1966 | 40.044 | 1965 | 40.501 | 1964 | 41.024 | 1963 | 41.432 | 1962 | 41.502 | 1961 | 41.451 | 1960 | 41.346 |
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