Year Percent 2002-01-01 2.38 2003-01-01 2.33 2004-01-01 2.36 2005-01-01 2.30 2006-01-01 2.25 2007-01-01 2.09 2008-01-01 2.21 2009-01-01 2.55 2010-01-01 2.61 2011-01-01 2.58 2012-01-01 2.79 2013-01-01 2.72 2014-01-01 2.84 2015-01-01 2.78