Year Percent 2005-01-01 74.300 2006-01-01 74.700 2007-01-01 75.000 2008-01-01 76.600 2009-01-01 77.100 2010-01-01 75.275 2011-01-01 76.275 2012-01-01 76.700 2013-01-01 77.075 2014-01-01 78.050 2015-01-01 78.625 2016-01-01 79.500 2017-01-01 79.350