Year Percent 2005-01-01 73.8014979400868 2006-01-01 76.1100052440545 2007-01-01 77.1723082165897 2008-01-01 78.2081616058238 2009-01-01 76.7083175244461 2010-01-01 78.5243689502982 2011-01-01 79.8052901830347 2012-01-01 82.0683700596588 2013-01-01 83.1350748586312 2014-01-01 82.4986151198343 2015-01-01 82.8858185478993 2016-01-01 81.6271126094510 2017-01-01 82.7499476366979