Year Percent 2002 5.6461 2003 4.0633 2004 4.4523 2005 4.0014 2006 3.883 2007 3.6747 2008 3.5577 2009 3.4524 2010 2.9114 2011 2.7923 2012 2.5497 2013 3.2048 2014 2.2451 2015 2.4844 2016 2.7739 2017 2.8584