Year | Value | 2021 | 11.4 | 2020 | 11.4 | 2019 | 11.6 | 2018 | 11.7 | 2017 | 11.9 | 2016 | 12.2 | 2015 | 11.9 | 2014 | 12.1 | 2013 | 12 | 2012 | 12 | 2011 | 11.6 | 2010 | 12 | 2009 | 14 | 2008 | 13.4 | 2007 | 12.7 | 2006 | 12.3 | 2005 | 12 | 2004 | 12.8 | 2003 | 13.6 | 2002 | 13.9 | 2001 | 14.6 | 2000 | 15.2 | 1999 | 14.6 | 1998 | 15.1 | 1997 | 14.4 | 1996 | 15 | 1995 | 15.4 | 1994 | 15.001 | 1993 | 15.166 | 1992 | 15.506 | 1991 | 15.611 | 1990 | 15.402 | 1989 | 15.645 | 1988 | 16.185 | 1987 | 16.748 | 1986 | 16.886 | 1985 | 16.899 | 1984 | 17.523 | 1983 | 17.941 | 1982 | 18.044 | 1981 | 18.059 | 1980 | 18.081 | 1979 | 18.009 | 1978 | 18.215 | 1977 | 18.65 | 1976 | 19.041 | 1975 | 19.43 | 1974 | 19.866 | 1973 | 20.385 | 1972 | 20.835 | 1971 | 20.879 | 1970 | 20.773 | 1969 | 21.288 | 1968 | 21.718 | 1967 | 22.49 | 1966 | 23.718 | 1965 | 24.779 | 1964 | 25.753 | 1963 | 26.826 | 1962 | 27.532 | 1961 | 27.892 | 1960 | 28.05 |
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