Year | Value | 2017 | 7.76 | 2016 | 9.99 | 2015 | 10.39 | 2014 | 10.43 | 2013 | 10.76 | 2012 | 11.5 | 2011 | 11.46 | 2010 | 11.62 | 2009 | 11.54 | 2008 | 11.85 | 2007 | 11.93 | 2006 | 11.91 | 2005 | 12.2 | 2004 | 12.86 | 2003 | 13.52 | 2002 | 14.4 | 2001 | 14.9 | 2000 | 15.7 | 1999 | 18.63 | 1998 | 20.35 | 1997 | 18.88 | 1996 | 19.42 | 1995 | 30.57 | 1994 | 23.41 | 1993 | 15.51 | 1992 | 28.13 | 1991 | 11.33 | 1990 | 16.47 | 1989 | 27.83 | 1988 | 19.97 |
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