Year | Value | 2021 | 12.432 | 2020 | 12.481 | 2019 | 12.894 | 2018 | 13.443 | 2017 | 13.805 | 2016 | 14.761 | 2015 | 14.899 | 2014 | 14.802 | 2013 | 13.59 | 2012 | 13.746 | 2011 | 13.864 | 2010 | 14.265 | 2009 | 14.342 | 2008 | 13.778 | 2007 | 13.207 | 2006 | 12.838 | 2005 | 12.607 | 2004 | 12.558 | 2003 | 11.903 | 2002 | 11.422 | 2001 | 11.508 | 2000 | 11.654 | 1999 | 11.934 | 1998 | 12.46 | 1997 | 13.123 | 1996 | 12.743 | 1995 | 13.41 | 1994 | 14.459 | 1993 | 15.214 | 1992 | 15.986 | 1991 | 16.481 | 1990 | 17.496 | 1989 | 18.458 | 1988 | 20.517 | 1987 | 22.216 | 1986 | 22.556 | 1985 | 22.41 | 1984 | 22.932 | 1983 | 22.486 | 1982 | 21.572 | 1981 | 21.12 | 1980 | 20.857 | 1979 | 20.74 | 1978 | 20.576 | 1977 | 20.661 | 1976 | 20.744 | 1975 | 20.837 | 1974 | 20.786 | 1973 | 20.492 | 1972 | 20.113 | 1971 | 19.748 | 1970 | 19.463 | 1969 | 19.299 | 1968 | 19.49 | 1967 | 19.909 | 1966 | 20.483 | 1965 | 21.183 | 1964 | 21.867 | 1963 | 23.803 | 1962 | 25.442 | 1961 | 27.352 | 1960 | 28.511 |
|