Year Percent 2005-01-01 77.225 2006-01-01 78.250 2007-01-01 79.125 2008-01-01 79.375 2009-01-01 77.725 2010-01-01 77.325 2011-01-01 77.250 2012-01-01 76.525 2013-01-01 75.850 2014-01-01 76.050 2015-01-01 76.575 2016-01-01 77.375 2017-01-01 78.125