Year | Value | 2022 | 4.479 | 2021 | 6.194 | 2020 | 5.623 | 2019 | 4.95 | 2018 | 5.741 | 2017 | 6.713 | 2016 | 8.374 | 2015 | 9.908 | 2014 | 11.858 | 2013 | 13.735 | 2012 | 15.451 | 2011 | 15.354 | 2010 | 14.534 | 2009 | 12.609 | 2008 | 6.774 | 2007 | 4.98 | 2006 | 4.415 | 2005 | 4.343 | 2004 | 4.491 | 2003 | 4.478 | 2002 | 4.216 | 2001 | 3.684 | 2000 | 4.318 | 1999 | 5.804 | 1998 | 7.699 | 1997 | 10.192 | 1996 | 11.692 | 1995 | 11.97 | 1994 | 14.544 | 1993 | 15.571 | 1992 | 15.021 | 1991 | 15.771 | 1990 | 14.077 | 1989 | 16.092 | 1988 | 17.431 | 1987 | 18.056 | 1986 | 18.02 | 1985 | 17.92 | 1984 | 16.438 | 1983 | 14.764 |
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