Year Percent 2004-01-01 20.625 2005-01-01 21.600 2006-01-01 19.250 2007-01-01 18.375 2008-01-01 18.875 2009-01-01 23.175 2010-01-01 26.825 2011-01-01 27.025 2012-01-01 33.750 2013-01-01 39.000 2014-01-01 41.300 2015-01-01 38.800 2016-01-01 36.475 2017-01-01 33.025