Year Percent 2005-01-01 78.8 2006-01-01 79.4 2007-01-01 79.9 2008-01-01 79.7 2009-01-01 77.8 2010-01-01 77.5 2011-01-01 77.8 2012-01-01 78.0 2013-01-01 78.1 2014-01-01 78.6 2015-01-01 78.9 2016-01-01 79.5