Year Percent 1998-01-01 7.30000 1999-01-01 7.40000 2000-01-01 6.70000 2001-01-01 6.70000 2002-01-01 7.50000 2003-01-01 8.40000 2004-01-01 6.90000 2005-01-01 6.90000 2006-01-01 6.90000 2007-01-01 6.90000 2008-01-01 6.90000 2009-01-01 6.90000 2010-01-01 6.90000 2011-01-01 10.82980 2012-01-01 9.45068 2013-01-01 10.80400 2014-01-01 10.88590 2015-01-01 10.58860