Year Percent 1998-01-01 7.5000 1999-01-01 11.4000 2000-01-01 12.3000 2001-01-01 12.3000 2002-01-01 12.3000 2003-01-01 12.3000 2004-01-01 12.3000 2005-01-01 12.3000 2006-01-01 13.5000 2007-01-01 12.9000 2008-01-01 14.3000 2009-01-01 14.7000 2010-01-01 15.2967 2011-01-01 15.2509 2012-01-01 14.9723 2013-01-01 14.8434 2014-01-01 14.9493 2015-01-01 14.3827 2016-01-01 14.1384