Year Percent 2001 13.68722 2002 14.41255 2003 14.27135 2004 14.6359 2005 13.80928 2006 14.21312 2007 15.69439 2008 16.11567 2009 14.9941 2010 15.53359 2011 14.82327 2012 14.4135 2013 15.38428