Year Percent 1998-01-01 11.7000 1999-01-01 13.2000 2000-01-01 12.9000 2001-01-01 13.5000 2002-01-01 13.8000 2003-01-01 13.8000 2004-01-01 15.4000 2005-01-01 14.6000 2006-01-01 13.2000 2007-01-01 12.0000 2008-01-01 11.2000 2009-01-01 13.3000 2010-01-01 13.8647 2011-01-01 13.1131 2012-01-01 14.7621 2013-01-01 15.6811 2014-01-01 14.6930 2015-01-01 15.9691 2016-01-01 17.1815