Year Percent 1991-01-01 1.3281399999999999 1992-01-01 1.3723500000000000 1993-01-01 1.5237399999999999 1994-01-01 1.6941000000000000 1995-01-01 1.9469400000000001 1996-01-01 1.6841599999999999 1997-01-01 1.7578500000000000 1998-01-01 1.6544100000000000 1999-01-01 1.5472500000000000 2000-01-01 1.8040500000000000 2001-01-01 1.7293100000000000 2002-01-01 1.7775400000000001 2003-01-01 1.6790700000000000 2004-01-01 1.6719900000000000 2005-01-01 1.6315800000000000 2006-01-01 1.5869600000000000 2007-01-01 1.6064100000000001 2008-01-01 1.6365900000000000 2009-01-01 1.6877900000000001 2010-01-01 1.5812800000000000 2011-01-01 1.5172700000000001 2012-01-01 1.6916900000000001 2013-01-01 1.7597099999999999 2014-01-01 1.5927799999999999 2015-01-01 1.4326800000000000 2016-01-01 1.3911799999999999