Year Percent 1998-01-01 12.4000 1999-01-01 12.0000 2000-01-01 12.1000 2001-01-01 12.6000 2002-01-01 12.2000 2003-01-01 12.4000 2004-01-01 12.2000 2005-01-01 11.9000 2006-01-01 11.2000 2007-01-01 11.7000 2008-01-01 10.1000 2009-01-01 12.8000 2010-01-01 14.1947 2011-01-01 13.5950 2012-01-01 14.5704 2013-01-01 15.5173 2014-01-01 16.4941 2015-01-01 18.9377 2016-01-01 22.0722