Year % 1990 25.87 1992 19.29 1993 13.29 1994 10.72 1995 21.21 1996 35.63 1997 14.16 1998 18.83 1999 13.43 2000 14.33 2001 12.5 2002 14.06 2003 11.2 2004 8.52 2005 7.43 2006 7.67 2007 6.42 2008 7.32 2009 6.6 2010 9.24 2011 6.54 2012 5.45 2013 5.06 2014 5.45 2015 5.52 2016 6.09 2017 6.58