Year | Value | 2023 | 20.353 | 2022 | 20.583 | 2021 | 20.414 | 2020 | 20.289 | 2019 | 20.131 | 2018 | 20.069 | 2017 | 19.991 | 2016 | 20.226 | 2015 | 20.254 | 2014 | 20.298 | 2013 | 20.55 | 2012 | 20.709 | 2011 | 21.114 | 2010 | 21.874 | 2009 | 22.829 | 2008 | 23.685 | 2007 | 24.526 | 2006 | 25.252 | 2005 | 26.055 | 2004 | 26.994 | 2003 | 27.745 | 2002 | 28.526 | 2001 | 29.174 | 2000 | 29.589 | 1999 | 29.865 | 1998 | 30.183 | 1997 | 30.377 | 1996 | 30.031 | 1995 | 30.355 | 1994 | 31.084 | 1993 | 31.405 | 1992 | 32.404 | 1991 | 33.635 | 1990 | 35.141 | 1989 | 36.221 | 1988 | 36.944 | 1987 | 38.238 | 1986 | 39.38 | 1985 | 40.685 | 1984 | 41.735 | 1983 | 42.644 | 1982 | 43.958 | 1981 | 44.581 | 1980 | 45.165 | 1979 | 45.597 | 1978 | 45.909 | 1977 | 46.409 | 1976 | 46.831 | 1975 | 47.216 |
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