Year % 1990 29 1992 29.04 1995 29.43 1998 28.68 2000 25.61 2002 27.56 2003 22.56 2004 22.86 2005 21.67 2006 21.32 2008 19 2009 19.32 2010 15.89 2011 13.74 2012 12.34 2013 12.16 2015 12.16 2016 7.65