Year Percent 1998-01-01 23.8000 1999-01-01 17.4000 2000-01-01 16.3000 2001-01-01 15.7000 2002-01-01 14.8000 2003-01-01 13.2000 2004-01-01 12.4000 2005-01-01 10.3000 2006-01-01 10.8000 2007-01-01 10.9000 2008-01-01 11.6000 2009-01-01 12.9000 2010-01-01 14.8252 2011-01-01 14.2437 2012-01-01 15.6536 2013-01-01 17.5697 2014-01-01 21.2927 2015-01-01 24.8348 2016-01-01 19.4113