Year Percent 1996 29.5 1997 22.85 1998 22.22 1999 22.48 2000 21.2 2001 21.86 2002 23.59 2003 21.92 2004 18.85 2007 11.75 2009 11.77 2010 13 2011 12.5 2012 12.12 2013 12.03 2014 16.53 2015 11.43 2016 10.41 2017 10.16