Year Percent 2005-01-01 83.6495478152182 2006-01-01 84.2064068161794 2007-01-01 83.7977003839722 2008-01-01 83.4340031032241 2009-01-01 82.6808338807535 2010-01-01 82.4478645762432 2011-01-01 82.3616254188638 2012-01-01 82.7200057594149 2013-01-01 82.4374152937846 2014-01-01 82.2050009761948 2015-01-01 81.9622017014214 2016-01-01 81.8449385130166 2017-01-01 81.7783866940969