Year | Value | 2021 | 8.838 | 2020 | 8.753 | 2019 | 8.658 | 2018 | 8.793 | 2017 | 8.954 | 2016 | 9.059 | 2015 | 9.715 | 2014 | 9.799 | 2013 | 9.482 | 2012 | 9.57 | 2011 | 9.741 | 2010 | 9.907 | 2009 | 10.115 | 2008 | 10.421 | 2007 | 10.765 | 2006 | 11.171 | 2005 | 11.599 | 2004 | 12.134 | 2003 | 13.852 | 2002 | 13.58 | 2001 | 14.312 | 2000 | 15.228 | 1999 | 16.141 | 1998 | 16.855 | 1997 | 17.565 | 1996 | 19.875 | 1995 | 20.233 | 1994 | 21.786 | 1993 | 21.512 | 1992 | 21.008 | 1991 | 21.006 | 1990 | 25.501 | 1989 | 20.475 | 1988 | 20.102 | 1987 | 19.738 | 1986 | 19.432 | 1985 | 19.688 | 1984 | 19.257 | 1983 | 19.419 | 1982 | 19.641 | 1981 | 19.94 | 1980 | 20.321 | 1979 | 20.654 | 1978 | 20.972 | 1977 | 21.362 | 1976 | 21.784 | 1975 | 22.149 | 1974 | 22.436 | 1973 | 22.797 | 1972 | 23.129 | 1971 | 23.577 | 1970 | 23.955 | 1969 | 24.363 | 1968 | 24.718 | 1967 | 25.015 | 1966 | 25.296 | 1965 | 25.52 | 1964 | 25.66 | 1963 | 25.723 | 1962 | 25.712 | 1961 | 25.683 | 1960 | 25.588 |
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