Year Percent 2003 19.35591 2004 16.29309 2005 24.15826 2006 23.13912 2007 30.49815 2008 40.29841 2009 32.21238 2010 52.35332 2011 64.00871 2012 37.86723 2013 30.37858 2014 22.67687 2015 25.29002 2016 25.10801