Year Percent 1998-01-01 55.7424 1999-01-01 64.9171 2000-01-01 81.9000 2001-01-01 72.1000 2002-01-01 46.2314 2003-01-01 68.2782 2004-01-01 59.7124 2005-01-01 60.7635 2006-01-01 62.4214 2007-01-01 64.9957 2008-01-01 53.3160 2009-01-01 66.6495 2010-01-01 40.7450 2011-01-01 71.3747 2012-01-01 68.7341 2013-01-01 71.3919 2014-01-01 66.1531 2015-01-01 58.1418 2016-01-01 58.0244