Year | Value | 2022 | 18.969 | 2021 | 19.334 | 2020 | 19.849 | 2019 | 20.28 | 2018 | 20.805 | 2017 | 21.348 | 2016 | 21.864 | 2015 | 22.343 | 2014 | 22.775 | 2013 | 23.035 | 2012 | 23.294 | 2011 | 23.369 | 2010 | 23.669 | 2009 | 24.084 | 2008 | 24.46 | 2007 | 24.894 | 2006 | 24.886 | 2005 | 25.191 | 2004 | 25.492 | 2003 | 25.876 | 2002 | 26.434 | 2001 | 26.924 | 2000 | 27.562 | 1999 | 28.663 | 1998 | 29.448 | 1997 | 31.65 | 1996 | 33.737 | 1995 | 36.187 | 1994 | 38.641 | 1993 | 40.789 | 1992 | 42.392 | 1991 | 43.803 | 1990 | 44.773 | 1989 | 45.605 | 1988 | 47.467 | 1987 | 48.699 | 1986 | 49.691 | 1985 | 50.641 | 1984 | 51.299 | 1983 | 50.975 | 1982 | 50.336 | 1981 | 49.09 | 1980 | 48.009 | 1979 | 37.88 | 1978 | 28.396 | 1977 | 23.051 | 1976 | 27.638 | 1975 | 31.169 | 1974 | 34.61 |
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