Year Percent 1996-12-31 5.8675 1997-12-31 6.4896 1998-12-31 7.1026 1999-12-31 5.1518 2000-12-31 5.8027 2001-12-31 4.9545 2002-12-31 3.824 2003-12-31 3.5448 2004-12-31 4.3269 2005-12-31 4.6201 2006-12-31 4.6408 2007-12-31 5.5431 2008-12-31 4.6311 2009-12-31 0.6065 2010-12-31 0.5151 2011-12-31 0.5105 2012-12-31 0.4529 2013-12-31 0.4406 2014-12-31 0.4457 2015-12-31 0.5028 2016-12-31 0.4109 2017-12-31 0.2696