Year | Value | 2023 | 23.117 | 2022 | 23.35 | 2021 | 23.507 | 2020 | 23.634 | 2019 | 23.849 | 2018 | 24.144 | 2017 | 24.514 | 2016 | 25.229 | 2015 | 25.834 | 2014 | 26.391 | 2013 | 26.866 | 2012 | 27.277 | 2011 | 27.656 | 2010 | 28.008 | 2009 | 28.398 | 2008 | 28.717 | 2007 | 29.038 | 2006 | 29.519 | 2005 | 30.013 | 2004 | 29.997 | 2003 | 29.887 | 2002 | 29.549 | 2001 | 29.364 | 2000 | 29.396 | 1999 | 29.638 | 1998 | 29.749 | 1997 | 29.847 | 1996 | 30.58 | 1995 | 31.432 | 1994 | 32.173 | 1993 | 32.659 | 1992 | 32.983 | 1991 | 33.174 | 1990 | 33.288 | 1989 | 33.362 | 1988 | 33.542 | 1987 | 33.677 | 1986 | 34.355 | 1985 | 34.924 | 1984 | 35.392 | 1983 | 35.617 | 1982 | 35.803 | 1981 | 36.003 | 1980 | 36.061 | 1979 | 36.101 | 1978 | 35.986 | 1977 | 35.736 | 1976 | 35.62 | 1975 | 35.806 |
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