Year | Value | 2021 | 11.48 | 2020 | 11.32 | 2019 | 11.96 | 2018 | 11.84 | 2017 | 12.38 | 2016 | 12.6 | 2015 | 13.23 | 2014 | 12.67 | 2013 | 13.2 | 2012 | 13.87 | 2011 | 14 | 2010 | 14.68 | 2009 | 14.53 | 2008 | 15.1 | 2007 | 15.15 | 2006 | 14.14 | 2005 | 13.96 | 2004 | 14.2 | 2003 | 13.94 | 2002 | 13.67 | 2001 | 14.36 | 2000 | 14.66 | 1999 | 14.87 | 1998 | 14.51 | 1997 | 15.23 | 1996 | 15.34 | 1995 | 15.77 | 1994 | 15.95 | 1993 | 16.53 | 1992 | 17.28 | 1991 | 17.4 | 1990 | 17.5 | 1989 | 17.5 | 1988 | 17.3 | 1987 | 16.8 | 1986 | 16.3 | 1985 | 15.9 | 1984 | 16 | 1983 | 15.8 | 1982 | 15.8 | 1981 | 16.2 | 1980 | 16.2 | 1979 | 16.8 | 1978 | 16.3 | 1977 | 17.3 | 1976 | 17.7 | 1975 | 18.3 | 1974 | 19.6 | 1973 | 20.5 | 1972 | 21.8 | 1971 | 22.6 | 1970 | 22.1 | 1969 | 22.3 | 1968 | 22.7 | 1967 | 22.5 | 1966 | 22.5 | 1965 | 22.9 | 1964 | 24.2 | 1963 | 25.5 | 1962 | 26.2 | 1961 | 27.1 | 1960 | 26.5 |
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