Year | Value | 2021 | 12.759 | 2020 | 12.924 | 2019 | 13.088 | 2018 | 13.777 | 2017 | 14.015 | 2016 | 14.508 | 2015 | 15.037 | 2014 | 15.58 | 2013 | 15.576 | 2012 | 16.231 | 2011 | 16.605 | 2010 | 17.38 | 2009 | 17.237 | 2008 | 17.606 | 2007 | 17.077 | 2006 | 17.738 | 2005 | 17.492 | 2004 | 17.574 | 2003 | 18.09 | 2002 | 19.322 | 2001 | 20.041 | 2000 | 20.628 | 1999 | 20.543 | 1998 | 19.865 | 1997 | 20.765 | 1996 | 21.931 | 1995 | 22.624 | 1994 | 24.125 | 1993 | 25.458 | 1992 | 26.139 | 1991 | 27.157 | 1990 | 28.663 | 1989 | 29.206 | 1988 | 31.243 | 1987 | 30.004 | 1986 | 30.452 | 1985 | 31.102 | 1984 | 30.346 | 1983 | 29.547 | 1982 | 29.479 | 1981 | 30.043 | 1980 | 29.576 | 1979 | 29.073 | 1978 | 29.383 | 1977 | 31.241 | 1976 | 31.899 | 1975 | 32.826 | 1974 | 33.873 | 1973 | 34.994 | 1972 | 36.044 | 1971 | 37.104 | 1970 | 38.18 | 1969 | 39.098 | 1968 | 39.674 | 1967 | 40.147 | 1966 | 40.581 | 1965 | 40.956 | 1964 | 41.179 | 1963 | 41.345 | 1962 | 41.561 | 1961 | 41.773 | 1960 | 42.004 |
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