Year Percent 1996-01-01 29.6012 1997-01-01 32.5292 1998-01-01 33.2823 1999-01-01 31.7598 2000-01-01 32.2329 2001-01-01 34.9637 2002-01-01 38.5435 2003-01-01 36.5364 2004-01-01 36.9699 2005-01-01 37.1915 2006-01-01 40.0176 2007-01-01 38.2675 2008-01-01 44.9591 2009-01-01 44.6463 2010-01-01 44.0038 2011-01-01 43.2412 2012-01-01 43.0732 2013-01-01 43.0024 2014-01-01 44.7541 2015-01-01 44.7085 2016-01-01 44.0558