Year Percent 1998-01-01 11.2899 1999-01-01 10.5617 2000-01-01 10.0072 2001-01-01 12.0698 2002-01-01 12.1433 2003-01-01 10.4899 2004-01-01 11.8006 2005-01-01 14.3269 2006-01-01 13.5517 2007-01-01 18.5168 2008-01-01 23.6345 2009-01-01 22.2228 2010-01-01 16.0535 2011-01-01 13.5680 2012-01-01 13.3701 2013-01-01 14.7643 2014-01-01 17.9851 2015-01-01 20.4669 2016-01-01 18.8068