Year Percent 2005-01-01 51.950 2006-01-01 51.425 2007-01-01 50.975 2008-01-01 50.475 2009-01-01 50.225 2010-01-01 50.150 2011-01-01 49.925 2012-01-01 49.475 2013-01-01 49.300 2014-01-01 49.275 2015-01-01 49.250 2016-01-01 48.900 2017-01-01 48.750