Year % 1990 28.33 1992 28.75 1995 29.77 1998 29.67 2000 27.09 2002 28.73 2003 24.48 2004 24.9 2005 12.1 2006 22.16 2008 21.32 2009 21.27 2010 18.15 2011 15.69 2012 14.94 2013 6.16 2015 5.97 2016 9.32