Year Percent 2002 4.67568 2003 4.19314 2004 4.03802 2005 3.75652 2006 3.34309 2007 3.22109 2008 2.80259 2009 2.97433 2010 3.83008 2011 4.60221 2012 5.35 2013 5.85924 2014 5.72516 2015 5.52519 2016 3.76197 2017 2.86986