Year | Value | 2021 | 6.8 | 2020 | 6.8 | 2019 | 7 | 2018 | 7.3 | 2017 | 7.6 | 2016 | 7.8 | 2015 | 8 | 2014 | 8.3 | 2013 | 8.5 | 2012 | 9 | 2011 | 9.2 | 2010 | 9.5 | 2009 | 9.6 | 2008 | 9.8 | 2007 | 9.7 | 2006 | 9.6 | 2005 | 9.6 | 2004 | 9.8 | 2003 | 9.5 | 2002 | 9.4 | 2001 | 9.4 | 2000 | 9.5 | 1999 | 9.4 | 1998 | 9.4 | 1997 | 9.4 | 1996 | 9.3 | 1995 | 9.2 | 1994 | 9.4 | 1993 | 9.7 | 1992 | 10 | 1991 | 9.9 | 1990 | 10 | 1989 | 9.9 | 1988 | 10.1 | 1987 | 9.7 | 1986 | 9.8 | 1985 | 10.2 | 1984 | 10.4 | 1983 | 10.6 | 1982 | 10.9 | 1981 | 11 | 1980 | 11.3 | 1979 | 11.9 | 1978 | 12.6 | 1977 | 13.2 | 1976 | 14 | 1975 | 14.9 | 1974 | 15.8 | 1973 | 16 | 1972 | 16.3 | 1971 | 16.8 | 1970 | 16.7 | 1969 | 17.4 | 1968 | 17.7 | 1967 | 17.9 | 1966 | 18.7 | 1965 | 19 | 1964 | 19.7 | 1963 | 18.7 | 1962 | 18.4 | 1961 | 18.4 | 1960 | 18.1 |
|