Year Percent 2005-01-01 55.600 2006-01-01 56.600 2007-01-01 58.100 2008-01-01 60.000 2009-01-01 59.600 2010-01-01 56.975 2011-01-01 58.400 2012-01-01 59.750 2013-01-01 61.300 2014-01-01 62.075 2015-01-01 63.925 2016-01-01 65.775 2017-01-01 65.750