Year | Value | 2021 | 11.8 | 2020 | 12.1 | 2019 | 12.3 | 2018 | 12.6 | 2017 | 12.8 | 2016 | 13 | 2015 | 13.2 | 2014 | 13.2 | 2013 | 13.1 | 2012 | 13.1 | 2011 | 13.8 | 2010 | 14.8 | 2009 | 15.3 | 2008 | 15.8 | 2007 | 16.4 | 2006 | 13.2 | 2005 | 14.8 | 2004 | 14.5 | 2003 | 14 | 2002 | 15.1 | 2001 | 13.1 | 2000 | 14.4 | 1999 | 16.1 | 1998 | 18 | 1997 | 17.2 | 1996 | 17.6 | 1995 | 18.7 | 1994 | 19.8 | 1993 | 20.9 | 1992 | 22 | 1991 | 21.1 | 1990 | 21.4 | 1989 | 21.7 | 1988 | 22 | 1987 | 22.3 | 1986 | 23.65 | 1985 | 25 | 1984 | 24.9 | 1983 | 24.8 | 1982 | 24.7 | 1981 | 25.25 | 1980 | 25.8 | 1979 | 26.35 | 1978 | 26.9 | 1977 | 26.75 | 1976 | 26.6 | 1975 | 28.1 | 1974 | 29.7 | 1973 | 30.1 | 1972 | 30.5 | 1971 | 30.8 | 1970 | 31.2 | 1969 | 31.6 | 1968 | 32 | 1967 | 32.3 | 1966 | 32.7 | 1965 | 33.1 | 1964 | 33.48 | 1963 | 33.86 | 1962 | 34.24 | 1961 | 34.62 | 1960 | 35 |
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