Year Percent 2002 16.50855 2003 15.41524 2004 14.52428 2005 15.4405 2006 15.70469 2007 15.49412 2008 15.36683 2009 14.73832 2010 13.69974 2011 14.24046 2012 16.0616 2013 15.35354 2015 16.17454 2016 15.39581