Year Percent 2002 15.17 2003 18.13 2004 19.74 2005 18.79 2006 17.1 2007 14.46 2008 11.22 2009 15.41 2010 17.83 2011 14.89 2012 13.1 2013 12.21 2014 9.31 2015 12.34 2016 10.97 2017 11.8 2018 9.6 2019 10.41 2020 10.86