Year Percent 1999-01-01 51.1662 2000-01-01 38.1000 2001-01-01 28.3000 2002-01-01 23.0016 2003-01-01 22.3954 2004-01-01 26.0784 2005-01-01 30.5286 2006-01-01 42.8669 2007-01-01 27.9902 2008-01-01 33.5168 2009-01-01 25.8923 2010-01-01 37.1845 2011-01-01 24.3717 2012-01-01 23.4179 2013-01-01 25.2889 2014-01-01 25.2568 2015-01-01 27.4093 2016-01-01 29.7276