Year % 1990 28.77 1992 28.76 1995 29.86 1998 31.29 2000 52.53 2002 55.87 2003 49.07 2004 46.75 2005 44.79 2006 45.72 2008 29.97 2009 26.26 2010 18.43 2011 23.35 2012 24.51 2013 19.47 2015 19.51 2016 22.75