Year Percent 1990-01-01 1.9702099999999998 1991-01-01 2.0743099999999997 1992-01-01 2.1519500000000000 1993-01-01 2.2878600000000000 1994-01-01 2.2944000000000000 1995-01-01 2.1633800000000000 1996-01-01 2.1698000000000000 1997-01-01 2.0638900000000002 1998-01-01 1.5924600000000000 1999-01-01 2.0619900000000000 2000-01-01 2.1677800000000000 2001-01-01 2.2592700000000000 2002-01-01 2.4193100000000000 2003-01-01 2.4707500000000000 2004-01-01 2.4590099999999997 2005-01-01 2.4312099999999996 2006-01-01 2.4383400000000000 2007-01-01 2.3764300000000000 2008-01-01 2.3318400000000000 2009-01-01 2.3258900000000002 2010-01-01 2.1913099999999996 2011-01-01 2.1850900000000000 2012-01-01 2.1720900000000003 2013-01-01 2.1212900000000000 2014-01-01 2.0384000000000000 2015-01-01 2.0402900000000000 2016-01-01 2.1466900000000000