Year | Value | 2021 | 10.604 | 2020 | 10.414 | 2019 | 10.09 | 2018 | 10.054 | 2017 | 10.023 | 2016 | 9.979 | 2015 | 10.905 | 2014 | 9.781 | 2013 | 9.992 | 2012 | 9.896 | 2011 | 9.845 | 2010 | 9.97 | 2009 | 10.167 | 2008 | 10.32 | 2007 | 10.5 | 2006 | 10.504 | 2005 | 10.719 | 2004 | 11.121 | 2003 | 11.871 | 2002 | 12.227 | 2001 | 12.239 | 2000 | 12.885 | 1999 | 13.854 | 1998 | 13.318 | 1997 | 13.781 | 1996 | 13.838 | 1995 | 14.261 | 1994 | 14.113 | 1993 | 14.899 | 1992 | 13.979 | 1991 | 14.529 | 1990 | 14.76 | 1989 | 15.653 | 1988 | 15.451 | 1987 | 15.908 | 1986 | 16.176 | 1985 | 16.498 | 1984 | 15.972 | 1983 | 15.855 | 1982 | 16.064 | 1981 | 15.872 | 1980 | 16.3 | 1979 | 16.513 | 1978 | 16.668 | 1977 | 16.731 | 1976 | 16.742 | 1975 | 16.819 | 1974 | 17.34 | 1973 | 17.034 | 1972 | 17.735 | 1971 | 17.363 | 1970 | 17.455 | 1969 | 17.62 | 1968 | 17.374 | 1967 | 17.182 | 1966 | 17.551 | 1965 | 17.555 | 1964 | 17.469 | 1963 | 18.043 | 1962 | 17.432 | 1961 | 17.589 | 1960 | 16.917 |
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