Year Percent 2000-01-01 4.150 2001-01-01 3.500 2002-01-01 4.125 2003-01-01 4.425 2004-01-01 4.350 2005-01-01 4.000 2006-01-01 4.075 2007-01-01 4.150 2008-01-01 6.275 2009-01-01 13.125 2010-01-01 15.375 2011-01-01 16.125 2012-01-01 15.875 2013-01-01 13.350 2014-01-01 11.350 2015-01-01 9.475 2016-01-01 7.925 2017-01-01 6.225