Year | Value | 2023 | 21.448 | 2022 | 21.62 | 2021 | 21.783 | 2020 | 21.938 | 2019 | 22.085 | 2018 | 22.223 | 2017 | 22.352 | 2016 | 22.472 | 2015 | 22.583 | 2014 | 22.686 | 2013 | 22.778 | 2012 | 22.862 | 2011 | 22.936 | 2010 | 23.001 | 2009 | 23.056 | 2008 | 23.101 | 2007 | 23.147 | 2006 | 23.193 | 2005 | 23.239 | 2004 | 23.284 | 2003 | 23.33 | 2002 | 23.376 | 2001 | 23.422 | 2000 | 23.468 | 1999 | 23.515 | 1998 | 23.561 | 1997 | 23.607 | 1996 | 23.653 | 1995 | 23.7 | 1994 | 23.746 | 1993 | 23.793 | 1992 | 23.839 | 1991 | 23.886 | 1990 | 24.043 | 1989 | 24.247 | 1988 | 24.452 | 1987 | 24.659 | 1986 | 24.866 | 1985 | 25.075 | 1984 | 25.285 | 1983 | 25.496 | 1982 | 26.058 | 1981 | 26.972 | 1980 | 27.904 | 1979 | 28.859 | 1978 | 29.831 | 1977 | 30.822 | 1976 | 31.83 | 1975 | 32.858 | 1974 | 33.901 |
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