Year Percent 2004-01-01 27.250 2005-01-01 27.575 2006-01-01 25.350 2007-01-01 23.300 2008-01-01 24.675 2009-01-01 28.475 2010-01-01 29.325 2011-01-01 32.025 2012-01-01 37.525 2013-01-01 41.350 2014-01-01 44.650 2015-01-01 42.500 2016-01-01 39.625 2017-01-01 37.325