Year Percent 2008-01-01 28.1007 2009-01-01 30.7950 2010-01-01 30.3892 2011-01-01 27.4457 2012-01-01 27.1104 2013-01-01 23.0532 2014-01-01 21.3843 2015-01-01 18.3975