Year | Value | 2021 | 10.313 | 2020 | 10.583 | 2019 | 10.794 | 2018 | 10.843 | 2017 | 10.994 | 2016 | 11.419 | 2015 | 11.208 | 2014 | 11.163 | 2013 | 11.088 | 2012 | 11.762 | 2011 | 11.507 | 2010 | 12.045 | 2009 | 12.286 | 2008 | 12.167 | 2007 | 11.821 | 2006 | 12.243 | 2005 | 11.882 | 2004 | 12.111 | 2003 | 11.949 | 2002 | 11.786 | 2001 | 12.182 | 2000 | 12.655 | 1999 | 12.872 | 1998 | 13.531 | 1997 | 14.258 | 1996 | 15.049 | 1995 | 15.763 | 1994 | 16.981 | 1993 | 17.812 | 1992 | 19.579 | 1991 | 18.649 | 1990 | 19.265 | 1989 | 19.105 | 1988 | 20.073 | 1987 | 19.553 | 1986 | 20.306 | 1985 | 20.363 | 1984 | 21.345 | 1983 | 21.458 | 1982 | 21.373 | 1981 | 18.728 | 1980 | 20.013 | 1979 | 18.469 | 1978 | 17.727 | 1977 | 17.53 | 1976 | 19.278 | 1975 | 17.201 | 1974 | 18.343 | 1973 | 18.789 | 1972 | 22.979 | 1971 | 22.963 | 1970 | 22.791 | 1969 | 23.459 | 1968 | 23.878 | 1967 | 24.106 | 1966 | 24.454 | 1965 | 24.811 | 1964 | 24.513 | 1963 | 25.184 | 1962 | 25.346 | 1961 | 26.15 | 1960 | 25.569 |
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