Year | Value | 2017 | 6.98 | 2016 | 8.9 | 2015 | 7.71 | 2014 | 7.35 | 2013 | 8.33 | 2012 | 8.07 | 2011 | 8.39 | 2010 | 8.87 | 2009 | 7.84 | 2008 | 8 | 2007 | 8.55 | 2006 | 8.98 | 2005 | 9.34 | 2004 | 9.66 | 2003 | 11.19 | 2002 | 11.44 | 2001 | 11.77 | 2000 | 12.71 | 1999 | 13.12 | 1998 | 12.23 | 1997 | 12.27 | 1996 | 13.29 | 1995 | 11.96 | 1994 | 11.86 | 1993 | 13.37 | 1992 | 14.66 | 1991 | 16.78 | 1990 | 33.5 | 1989 | 42.92 |
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