Year Percent 2005-01-01 39.375 2006-01-01 40.050 2007-01-01 41.025 2008-01-01 40.525 2009-01-01 36.850 2010-01-01 35.500 2011-01-01 35.000 2012-01-01 33.625 2013-01-01 32.775 2014-01-01 32.325 2015-01-01 32.450 2016-01-01 32.975 2017-01-01 33.925