Year | Value | 2021 | 11.687 | 2020 | 11.946 | 2019 | 12.359 | 2018 | 12.557 | 2017 | 12.909 | 2016 | 13.292 | 2015 | 13.604 | 2014 | 13.958 | 2013 | 14.282 | 2012 | 14.572 | 2011 | 14.781 | 2010 | 14.842 | 2009 | 14.879 | 2008 | 15.191 | 2007 | 15.224 | 2006 | 15.087 | 2005 | 14.903 | 2004 | 14.892 | 2003 | 14.996 | 2002 | 15.022 | 2001 | 15.147 | 2000 | 15.211 | 1999 | 15.248 | 1998 | 15.211 | 1997 | 15.367 | 1996 | 15.769 | 1995 | 16.251 | 1994 | 17.058 | 1993 | 17.808 | 1992 | 18.793 | 1991 | 19.577 | 1990 | 20.582 | 1989 | 22.016 | 1988 | 23.674 | 1987 | 25.338 | 1986 | 26.879 | 1985 | 27.904 | 1984 | 28.282 | 1983 | 29.327 | 1982 | 29.97 | 1981 | 30.118 | 1980 | 29.626 | 1979 | 29.196 | 1978 | 28.497 | 1977 | 27.758 | 1976 | 27.396 | 1975 | 27.172 | 1974 | 27.477 | 1973 | 28.028 | 1972 | 28.211 | 1971 | 27.38 | 1970 | 26.675 | 1969 | 26.643 | 1968 | 28.186 | 1967 | 28.887 | 1966 | 30.291 | 1965 | 32.066 | 1964 | 33.732 | 1963 | 35.139 | 1962 | 36.315 | 1961 | 36.987 | 1960 | 37.307 |
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