Year Percent 2005-01-01 57.2155964271837 2006-01-01 57.9863508427112 2007-01-01 57.9202180445084 2008-01-01 57.6157856808251 2009-01-01 56.6802172786923 2010-01-01 56.4974781692165 2011-01-01 56.6625665122700 2012-01-01 57.4549935249386 2013-01-01 57.3136697725193 2014-01-01 56.8861398896491 2015-01-01 57.2142203278072 2016-01-01 57.3721223947245 2017-01-01 57.3090230054105