Year | Value | 2022 | 15.602 | 2021 | 15.848 | 2020 | 16.097 | 2019 | 16.348 | 2018 | 16.602 | 2017 | 16.857 | 2016 | 17.114 | 2015 | 17.374 | 2014 | 17.635 | 2013 | 17.898 | 2012 | 18.163 | 2011 | 18.43 | 2010 | 18.698 | 2009 | 18.969 | 2008 | 19.243 | 2007 | 19.521 | 2006 | 19.801 | 2005 | 20.085 | 2004 | 20.371 | 2003 | 20.661 | 2002 | 20.953 | 2001 | 21.249 | 2000 | 21.349 | 1999 | 21.409 | 1998 | 21.468 | 1997 | 21.528 | 1996 | 21.587 | 1995 | 21.647 | 1994 | 21.707 | 1993 | 21.768 | 1992 | 21.828 | 1991 | 21.888 | 1990 | 21.86 | 1989 | 21.81 | 1988 | 21.76 | 1987 | 21.71 | 1986 | 21.66 | 1985 | 21.61 | 1984 | 21.56 | 1983 | 21.511 | 1982 | 21.461 | 1981 | 21.412 | 1980 | 21.519 | 1979 | 21.677 | 1978 | 21.836 | 1977 | 21.995 | 1976 | 22.156 | 1975 | 22.317 | 1974 | 22.479 | 1973 | 22.642 | 1972 | 22.805 | 1971 | 22.97 | 1970 | 22.883 | 1969 | 22.741 | 1968 | 22.6 | 1967 | 22.459 | 1966 | 22.318 | 1965 | 22.179 | 1964 | 22.04 | 1963 | 21.901 | 1962 | 21.763 | 1961 | 21.626 | 1960 | 21.556 |
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