Year | Value | 2021 | 17.976 | 2020 | 17.881 | 2019 | 18.886 | 2018 | 21.015 | 2017 | 21.129 | 2016 | 21.36 | 2015 | 21.709 | 2014 | 22.097 | 2013 | 22.335 | 2012 | 22.43 | 2011 | 22.53 | 2010 | 22.533 | 2009 | 23.264 | 2008 | 24.033 | 2007 | 24.595 | 2006 | 25.459 | 2005 | 26.673 | 2004 | 27.2 | 2003 | 28.036 | 2002 | 29.185 | 2001 | 29.845 | 2000 | 30.388 | 1999 | 30.938 | 1998 | 31.322 | 1997 | 31.787 | 1996 | 31.624 | 1995 | 32.256 | 1994 | 32.322 | 1993 | 33.519 | 1992 | 34.308 | 1991 | 35.269 | 1990 | 36.532 | 1989 | 36.731 | 1988 | 36.621 | 1987 | 36.761 | 1986 | 37.381 | 1985 | 37.935 | 1984 | 38.955 | 1983 | 40.134 | 1982 | 41.014 | 1981 | 40.846 | 1980 | 41.099 | 1979 | 41.232 | 1978 | 41.259 | 1977 | 41.041 | 1976 | 40.709 | 1975 | 40.217 | 1974 | 39.958 | 1973 | 39.615 | 1972 | 39.304 | 1971 | 38.901 | 1970 | 38.576 | 1969 | 38.548 | 1968 | 38.786 | 1967 | 39.22 | 1966 | 39.835 | 1965 | 40.564 | 1964 | 41.376 | 1963 | 42.262 | 1962 | 43.17 | 1961 | 44.077 | 1960 | 44.847 |
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