Year | Value | 2024 | 17.161 | 2023 | 17.592 | 2022 | 18.044 | 2021 | 18.517 | 2020 | 19.012 | 2019 | 19.53 | 2018 | 20.07 | 2017 | 20.635 | 2016 | 21.225 | 2015 | 21.841 | 2014 | 22.483 | 2013 | 23.138 | 2012 | 23.806 | 2011 | 24.489 | 2010 | 25.183 | 2009 | 25.891 | 2008 | 26.611 | 2007 | 27.345 | 2006 | 28.09 | 2005 | 28.848 | 2004 | 29.617 | 2003 | 30.4 | 2002 | 30.153 | 2001 | 29.907 | 2000 | 29.662 | 1999 | 29.418 | 1998 | 29.175 | 1997 | 28.934 | 1996 | 28.694 | 1995 | 28.569 | 1994 | 28.931 | 1993 | 29.296 | 1992 | 29.663 | 1991 | 30.034 | 1990 | 30.407 | 1989 | 30.76 | 1988 | 31.108 | 1987 | 31.459 | 1986 | 31.812 | 1985 | 32.62 | 1984 | 33.591 | 1983 | 34.579 | 1982 | 35.578 | 1981 | 36.591 | 1980 | 37.458 | 1979 | 37.737 | 1978 | 38.017 | 1977 | 38.298 | 1976 | 38.579 | 1975 | 38.862 |
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