Year Percent 1996-01-01 48.6944 1997-01-01 43.2750 1998-01-01 47.0376 1999-01-01 53.3281 2000-01-01 59.8968 2001-01-01 59.9084 2002-01-01 59.9370 2003-01-01 53.0558 2004-01-01 44.9516 2005-01-01 42.8801 2006-01-01 43.4671 2007-01-01 49.3454 2008-01-01 38.7748 2009-01-01 30.7876 2010-01-01 30.6343 2011-01-01 29.9115 2012-01-01 46.8084 2013-01-01 43.3226 2014-01-01 38.2423 2015-01-01 42.2901 2016-01-01 37.4314