Year Percent 2005-01-01 81.300 2006-01-01 81.200 2007-01-01 81.900 2008-01-01 83.600 2009-01-01 83.900 2010-01-01 81.950 2011-01-01 82.850 2012-01-01 83.600 2013-01-01 83.550 2014-01-01 84.750 2015-01-01 84.825 2016-01-01 85.525 2017-01-01 85.550