Year Percent 2005-01-01 51.8116816591893 2006-01-01 52.3192688562598 2007-01-01 52.5681088031819 2008-01-01 52.5501833606456 2009-01-01 51.8779231229489 2010-01-01 52.0477815992203 2011-01-01 52.5081991594418 2012-01-01 53.1695734817203 2013-01-01 53.0432801075557 2014-01-01 53.0267581964351 2015-01-01 53.5358307679299 2016-01-01 53.9583758258698 2017-01-01 54.3335831639181