Year Percent 2003-01-01 79.900 2004-01-01 78.600 2005-01-01 81.275 2006-01-01 81.225 2007-01-01 80.575 2008-01-01 77.675 2009-01-01 77.675 2010-01-01 79.075 2011-01-01 79.150 2012-01-01 77.975 2013-01-01 77.750 2014-01-01 83.375 2015-01-01 83.250 2016-01-01 80.500 2017-01-01 79.925