Year | Value | 2021 | 12.504 | 2020 | 12.486 | 2019 | 12.369 | 2018 | 12.671 | 2017 | 13.043 | 2016 | 13.291 | 2015 | 13.693 | 2014 | 14.022 | 2013 | 14.373 | 2012 | 14.634 | 2011 | 15.056 | 2010 | 15.421 | 2009 | 15.765 | 2008 | 16.007 | 2007 | 16.301 | 2006 | 16.707 | 2005 | 16.827 | 2004 | 16.982 | 2003 | 17.118 | 2002 | 17.441 | 2001 | 17.695 | 2000 | 18.088 | 1999 | 18.305 | 1998 | 18.548 | 1997 | 18.692 | 1996 | 18.909 | 1995 | 19.195 | 1994 | 19.537 | 1993 | 19.718 | 1992 | 19.852 | 1991 | 20.029 | 1990 | 20.737 | 1989 | 20.086 | 1988 | 20.154 | 1987 | 21.846 | 1986 | 20.423 | 1985 | 20.723 | 1984 | 20.987 | 1983 | 21.06 | 1982 | 21.378 | 1981 | 21.89 | 1980 | 22.103 | 1979 | 22.356 | 1978 | 22.66 | 1977 | 22.922 | 1976 | 23.139 | 1975 | 23.374 | 1974 | 23.463 | 1973 | 23.458 | 1972 | 23.59 | 1971 | 24.447 | 1970 | 24.061 | 1969 | 24.308 | 1968 | 24.596 | 1967 | 24.97 | 1966 | 25.278 | 1965 | 25.412 | 1964 | 25.271 | 1963 | 25.551 | 1962 | 25.817 | 1961 | 26.049 | 1960 | 26.335 |
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