Year Percent 1992-01-01 2.4349800000000000 1993-01-01 2.5174400000000000 1994-01-01 2.5100100000000000 1995-01-01 2.5098000000000000 1996-01-01 2.4806300000000000 1997-01-01 2.4401700000000000 1998-01-01 2.3329400000000002 1999-01-01 2.2238900000000004 2000-01-01 2.1645800000000000 2001-01-01 2.2116900000000000 2002-01-01 2.2926800000000000 2003-01-01 2.3945300000000000 2004-01-01 2.4338900000000003 2005-01-01 2.4360600000000000 2006-01-01 2.3776800000000000 2007-01-01 2.3153000000000000 2008-01-01 2.3082700000000003 2009-01-01 2.3798200000000000 2010-01-01 2.3438900000000000 2011-01-01 2.3201500000000000 2012-01-01 2.3371100000000000 2013-01-01 2.3515400000000000 2014-01-01 2.2715300000000000 2015-01-01 2.2347900000000003 2016-01-01 2.2032900000000000