Year | Value | 2021 | 13.412 | 2020 | 12.966 | 2019 | 13.451 | 2018 | 14.395 | 2017 | 14.856 | 2016 | 15.471 | 2015 | 15.79 | 2014 | 15.442 | 2013 | 15.102 | 2012 | 14.842 | 2011 | 14.937 | 2010 | 15.109 | 2009 | 14.789 | 2008 | 13.9 | 2007 | 13.122 | 2006 | 12.648 | 2005 | 12.483 | 2004 | 12.221 | 2003 | 11.811 | 2002 | 11.798 | 2001 | 11.77 | 2000 | 11.979 | 1999 | 12.185 | 1998 | 12.637 | 1997 | 13.1 | 1996 | 13.553 | 1995 | 14.088 | 1994 | 14.652 | 1993 | 15.481 | 1992 | 16.552 | 1991 | 17.795 | 1990 | 18.462 | 1989 | 18.312 | 1988 | 18.418 | 1987 | 18.889 | 1986 | 19.689 | 1985 | 20.012 | 1984 | 19.976 | 1983 | 19.684 | 1982 | 19.494 | 1981 | 19.4 | 1980 | 19.318 | 1979 | 19.143 | 1978 | 19.004 | 1977 | 18.806 | 1976 | 18.884 | 1975 | 18.957 | 1974 | 18.852 | 1973 | 19.069 | 1972 | 19.329 | 1971 | 19.408 | 1970 | 19.305 | 1969 | 19.334 | 1968 | 19.642 | 1967 | 20.429 | 1966 | 20.992 | 1965 | 21.917 | 1964 | 23.428 | 1963 | 24.933 | 1962 | 25.647 | 1961 | 26.344 | 1960 | 26.737 |
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