Year Percent 2003-01-01 83.000 2004-01-01 81.750 2005-01-01 84.300 2006-01-01 84.350 2007-01-01 84.675 2008-01-01 82.925 2009-01-01 80.200 2010-01-01 79.825 2011-01-01 79.175 2012-01-01 79.075 2013-01-01 81.150 2014-01-01 84.800 2015-01-01 84.725 2016-01-01 84.575 2017-01-01 83.875