Year Percent 1998-01-01 10.3000 1999-01-01 10.8000 2000-01-01 13.2000 2001-01-01 13.0000 2002-01-01 12.2000 2003-01-01 13.0000 2004-01-01 14.2000 2005-01-01 17.1000 2006-01-01 15.4000 2007-01-01 16.0000 2008-01-01 15.4000 2009-01-01 17.2000 2010-01-01 17.3385 2011-01-01 16.8781 2012-01-01 18.0800 2013-01-01 16.9634 2014-01-01 16.9984 2015-01-01 16.8745 2016-01-01 17.5152