Year | Value | 2021 | 17.473 | 2020 | 18.238 | 2019 | 18.451 | 2018 | 18.703 | 2017 | 18.903 | 2016 | 18.972 | 2015 | 19.524 | 2014 | 20.161 | 2013 | 20.754 | 2012 | 21.245 | 2011 | 21.634 | 2010 | 21.894 | 2009 | 22.307 | 2008 | 22.749 | 2007 | 23.242 | 2006 | 23.114 | 2005 | 23.058 | 2004 | 23.8 | 2003 | 24.794 | 2002 | 25.896 | 2001 | 26.852 | 2000 | 27.656 | 1999 | 28.021 | 1998 | 28.455 | 1997 | 28.901 | 1996 | 29.392 | 1995 | 30.016 | 1994 | 30.762 | 1993 | 31.547 | 1992 | 32.423 | 1991 | 33.423 | 1990 | 34.413 | 1989 | 35.442 | 1988 | 36.449 | 1987 | 37.343 | 1986 | 38.375 | 1985 | 39.306 | 1984 | 40.197 | 1983 | 40.987 | 1982 | 41.727 | 1981 | 42.454 | 1980 | 43.154 | 1979 | 43.891 | 1978 | 44.738 | 1977 | 45.717 | 1976 | 46.852 | 1975 | 48.191 | 1974 | 48.612 | 1973 | 49.033 | 1972 | 49.416 | 1971 | 49.617 | 1970 | 49.833 | 1969 | 50.027 | 1968 | 50.287 | 1967 | 50.606 | 1966 | 50.644 | 1965 | 50.763 | 1964 | 50.985 | 1963 | 50.985 | 1962 | 51.031 | 1961 | 51.189 | 1960 | 51.321 |
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