Year Percent 2000 10.36 2001 10.84 2002 9.33 2003 8.19 2004 8.94 2005 7.04 2006 5.41 2007 5.02 2008 4.84 2009 5.36 2010 5.08 2011 4.84 2012 4.61 2013 4.55 2014 4.87 2015 4.53 2016 4.57 2017 4.51