Year Percent 2005-01-01 92.0 2006-01-01 92.1 2007-01-01 92.1 2008-01-01 92.1 2009-01-01 91.7 2010-01-01 91.5 2011-01-01 91.4 2012-01-01 91.4 2013-01-01 91.3 2014-01-01 91.2 2015-01-01 91.3 2016-01-01 91.3