Year | Value | 2021 | 8.6 | 2020 | 8.7 | 2019 | 10.1 | 2018 | 10.5 | 2017 | 9.7 | 2016 | 11.2 | 2015 | 11.9 | 2014 | 12.6 | 2013 | 12.7 | 2012 | 13.4 | 2011 | 13.1 | 2010 | 13.6 | 2009 | 13 | 2008 | 13.8 | 2007 | 13.4 | 2006 | 13.6 | 2005 | 14.673 | 2004 | 14.755 | 2003 | 14.87 | 2002 | 14.988 | 2001 | 15.155 | 2000 | 15.371 | 1999 | 15.615 | 1998 | 15.886 | 1997 | 16.209 | 1996 | 16.64 | 1995 | 17.185 | 1994 | 17.778 | 1993 | 18.423 | 1992 | 19.143 | 1991 | 19.731 | 1990 | 20.212 | 1989 | 20.564 | 1988 | 20.79 | 1987 | 20.907 | 1986 | 20.927 | 1985 | 20.878 | 1984 | 20.794 | 1983 | 20.707 | 1982 | 20.643 | 1981 | 20.57 | 1980 | 20.556 | 1979 | 20.591 | 1978 | 20.64 | 1977 | 20.733 | 1976 | 20.883 | 1975 | 21.139 | 1974 | 21.555 | 1973 | 22.129 | 1972 | 22.793 | 1971 | 23.674 | 1970 | 24.646 | 1969 | 25.605 | 1968 | 26.508 | 1967 | 27.292 | 1966 | 27.997 | 1965 | 28.593 | 1964 | 29.2 | 1963 | 29.863 | 1962 | 30.614 | 1961 | 31.487 | 1960 | 32.481 |
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