Year | Value | 2017 | 6.19 | 2016 | 6.97 | 2015 | 7.02 | 2014 | 6.49 | 2013 | 7.7 | 2012 | 7.76 | 2011 | 8.09 | 2010 | 8.01 | 2009 | 8.18 | 2008 | 8.65 | 2007 | 8.8 | 2006 | 8.47 | 2005 | 9.73 | 2004 | 10.28 | 2003 | 11.46 | 2002 | 11.61 | 2001 | 11.99 | 2000 | 14.11 | 1999 | 14.86 | 1998 | 13.56 | 1997 | 13.46 | 1996 | 14.45 | 1995 | 14.79 | 1994 | 17.19 | 1993 | 19.14 | 1992 | 25.91 | 1991 | 19.81 | 1990 | 19.8 | 1989 | 41.88 | 1988 | 17.32 |
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