Year Percent 2006-01-01 76.600 2007-01-01 76.525 2008-01-01 75.625 2009-01-01 75.100 2010-01-01 74.475 2011-01-01 73.825 2012-01-01 74.775 2013-01-01 73.200 2014-01-01 72.350 2015-01-01 70.450 2016-01-01 69.650 2017-01-01 69.025