Year Percent 2003-01-01 30.300 2004-01-01 30.400 2005-01-01 31.700 2006-01-01 33.200 2007-01-01 32.000 2008-01-01 34.075 2009-01-01 38.200 2010-01-01 39.650 2011-01-01 39.300 2012-01-01 41.000 2013-01-01 40.450 2014-01-01 42.550 2015-01-01 38.450 2016-01-01 39.550 2017-01-01 39.750