Year | Value | 2022 | 14.414 | 2021 | 15.053 | 2020 | 15.768 | 2019 | 16.483 | 2018 | 17.022 | 2017 | 17.423 | 2016 | 17.927 | 2015 | 18.462 | 2014 | 19.087 | 2013 | 19.986 | 2012 | 20.904 | 2011 | 18.562 | 2010 | 18.63 | 2009 | 19.146 | 2008 | 19.77 | 2007 | 20.308 | 2006 | 20.9 | 2005 | 21.476 | 2004 | 22.094 | 2003 | 22.709 | 2002 | 23.284 | 2001 | 23.932 | 2000 | 24.587 | 1999 | 25.035 | 1998 | 25.358 | 1997 | 25.792 | 1996 | 26.3 | 1995 | 26.977 | 1994 | 27.948 | 1993 | 29.024 | 1992 | 30.382 | 1991 | 31.883 | 1990 | 33.522 | 1989 | 34.424 | 1988 | 35.012 | 1987 | 35.139 | 1986 | 34.981 | 1985 | 34.77 | 1984 | 34 | 1983 | 32.556 | 1982 | 30.888 | 1981 | 32.021 | 1980 | 32.936 | 1979 | 33.538 | 1978 | 33.907 | 1977 | 34.163 | 1976 | 34.104 | 1975 | 33.821 | 1974 | 34.591 |
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