Year Percent 1998-01-01 36.7877 1999-01-01 38.1347 2000-01-01 31.2000 2001-01-01 21.9000 2002-01-01 30.6716 2003-01-01 23.6619 2004-01-01 31.3308 2005-01-01 29.5203 2006-01-01 30.8284 2007-01-01 40.7373 2008-01-01 27.3716 2009-01-01 26.2423 2010-01-01 39.3815 2011-01-01 37.8618 2012-01-01 45.0949 2013-01-01 44.8241 2014-01-01 54.8987 2015-01-01 48.1398 2016-01-01 46.7813