Year Percent 2005-01-01 50.950 2006-01-01 50.500 2007-01-01 50.325 2008-01-01 49.975 2009-01-01 49.700 2010-01-01 49.650 2011-01-01 49.450 2012-01-01 49.075 2013-01-01 48.900 2014-01-01 48.725 2015-01-01 48.700 2016-01-01 48.450 2017-01-01 48.175