Year | Value | 2022 | 18.573 | 2021 | 18.586 | 2020 | 18.586 | 2019 | 18.57 | 2018 | 18.541 | 2017 | 18.497 | 2016 | 18.438 | 2015 | 18.366 | 2014 | 18.293 | 2013 | 18.221 | 2012 | 18.149 | 2011 | 18.077 | 2010 | 18.064 | 2009 | 18.165 | 2008 | 18.267 | 2007 | 18.369 | 2006 | 18.472 | 2005 | 18.655 | 2004 | 18.998 | 2003 | 19.348 | 2002 | 19.701 | 2001 | 20.06 | 2000 | 20.379 | 1999 | 20.616 | 1998 | 20.855 | 1997 | 21.095 | 1996 | 21.338 | 1995 | 21.761 | 1994 | 22.548 | 1993 | 23.355 | 1992 | 24.18 | 1991 | 25.028 | 1990 | 26.156 | 1989 | 27.852 | 1988 | 29.611 | 1987 | 31.437 | 1986 | 33.321 | 1985 | 35.124 | 1984 | 36.699 | 1983 | 38.307 | 1982 | 39.939 | 1981 | 41.593 | 1980 | 43.28 | 1979 | 45.019 | 1978 | 46.767 | 1977 | 48.524 | 1976 | 50.281 | 1975 | 51.967 | 1974 | 53.421 | 1973 | 54.869 | 1972 | 56.308 | 1971 | 57.739 | 1970 | 59.296 | 1969 | 61.244 | 1968 | 63.154 | 1967 | 65.029 | 1966 | 66.653 | 1965 | 67.649 | 1964 | 68.628 | 1963 | 69.593 | 1962 | 70.539 | 1961 | 71.469 | 1960 | 72.29 |
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