Year Percent 1999-01-01 16.325 2000-01-01 18.975 2001-01-01 19.825 2002-01-01 18.700 2003-01-01 17.450 2004-01-01 17.475 2005-01-01 15.475 2006-01-01 12.325 2007-01-01 9.925 2008-01-01 8.400 2009-01-01 11.400 2010-01-01 14.250 2011-01-01 13.700 2012-01-01 13.575 2013-01-01 14.025 2014-01-01 12.875 2015-01-01 10.400 2016-01-01 8.800 2017-01-01 7.975