Year | Value | 2021 | 14.088 | 2020 | 14.576 | 2019 | 15.001 | 2018 | 15.531 | 2017 | 16.126 | 2016 | 16.794 | 2015 | 17.465 | 2014 | 18.044 | 2013 | 18.895 | 2012 | 19.865 | 2011 | 20.527 | 2010 | 21.165 | 2009 | 21.644 | 2008 | 21.371 | 2007 | 20.554 | 2006 | 19.584 | 2005 | 18.989 | 2004 | 18.861 | 2003 | 18.791 | 2002 | 18.952 | 2001 | 19.464 | 2000 | 20.539 | 1999 | 22.103 | 1998 | 24.013 | 1997 | 25.971 | 1996 | 28.24 | 1995 | 30.575 | 1994 | 32.731 | 1993 | 34.903 | 1992 | 36.998 | 1991 | 39.144 | 1990 | 41.294 | 1989 | 43.043 | 1988 | 44.562 | 1987 | 45.796 | 1986 | 46.813 | 1985 | 47.495 | 1984 | 47.448 | 1983 | 47.311 | 1982 | 46.915 | 1981 | 46.606 | 1980 | 46.636 | 1979 | 46.7 | 1978 | 46.798 | 1977 | 46.799 | 1976 | 46.748 | 1975 | 46.784 | 1974 | 47.223 | 1973 | 47.385 | 1972 | 47.219 | 1971 | 47.72 | 1970 | 48.302 | 1969 | 48.661 | 1968 | 49.113 | 1967 | 49.687 | 1966 | 50.295 | 1965 | 51.021 | 1964 | 51.591 | 1963 | 51.969 | 1962 | 52.185 | 1961 | 52.044 | 1960 | 51.927 |
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