Year | Value | 2022 | 14.468 | 2021 | 14.678 | 2020 | 15.033 | 2019 | 15.594 | 2018 | 16.481 | 2017 | 17.368 | 2016 | 17.739 | 2015 | 17.939 | 2014 | 17.972 | 2013 | 17.737 | 2012 | 17.664 | 2011 | 17.638 | 2010 | 17.746 | 2009 | 18.06 | 2008 | 18.315 | 2007 | 18.55 | 2006 | 18.899 | 2005 | 18.901 | 2004 | 18.922 | 2003 | 18.995 | 2002 | 19.803 | 2001 | 21.583 | 2000 | 21.436 | 1999 | 22.264 | 1998 | 22.977 | 1997 | 23.45 | 1996 | 24.029 | 1995 | 23.953 | 1994 | 24.328 | 1993 | 24.528 | 1992 | 24.67 | 1991 | 25.47 | 1990 | 25.874 | 1989 | 26.82 | 1988 | 27.427 | 1987 | 28.027 | 1986 | 28.79 | 1985 | 29.453 | 1984 | 30.207 | 1983 | 30.897 | 1982 | 31.71 | 1981 | 32.634 | 1980 | 33.376 | 1979 | 34.121 | 1978 | 34.56 | 1977 | 34.851 | 1976 | 35.578 | 1975 | 36.481 | 1974 | 37.52 |
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