Year | Value | 2022 | 7.877 | 2021 | 9.301 | 2020 | 10.33 | 2019 | 8.734 | 2018 | 8.336 | 2017 | 7.89 | 2016 | 7.841 | 2015 | 7.488 | 2014 | 6.547 | 2013 | 6.444 | 2012 | 6.451 | 2011 | 6.307 | 2010 | 7.158 | 2009 | 7.74 | 2008 | 8.026 | 2007 | 9.403 | 2006 | 10.844 | 2005 | 12.009 | 2004 | 12.98 | 2003 | 16.661 | 2002 | 16.648 | 2001 | 15.052 | 2000 | 12.627 | 1999 | 10.466 | 1998 | 9.362 | 1997 | 11.44 | 1996 | 10.85 | 1995 | 10.02 | 1994 | 9.04 | 1993 | 8.35 | 1992 | 8.96 | 1991 | 8.95 | 1990 | 8.53 | 1987 | 9.1 | 1986 | 10.7 | 1984 | 9.94 | 1982 | 11.7 | 1981 | 6.6 | 1980 | 7.3 | 1974 | 8.1 | 1973 | 8.9 | 1972 | 7.7 | 1971 | 7.6 | 1970 | 7.5 |
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