Year | Value | 2017 | 6.84 | 2016 | 8.27 | 2015 | 7.61 | 2014 | 8.74 | 2013 | 8.17 | 2012 | 8.36 | 2011 | 9.33 | 2010 | 9.36 | 2009 | 9.49 | 2008 | 9.5 | 2007 | 9.97 | 2006 | 10.87 | 2005 | 11.45 | 2004 | 13.24 | 2003 | 14.5 | 2002 | 16.62 | 2001 | 15.31 | 2000 | 17.05 | 1999 | 17.35 | 1998 | 17.5 | 1997 | 16.48 | 1996 | 14.35 | 1995 | 22.36 | 1994 | 28.38 | 1993 | 23.36 | 1992 | 32.31 | 1990 | 33.33 | 1989 | 33.85 | 1988 | 27.57 |
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