Year Percent 1990-01-01 2.6134200000000000 1991-01-01 2.8613000000000000 1992-01-01 2.9089500000000000 1993-01-01 2.7710900000000000 1994-01-01 2.7295400000000000 1995-01-01 2.6052700000000000 1996-01-01 2.4867100000000000 1997-01-01 2.2707700000000000 1998-01-01 2.1353700000000000 1999-01-01 2.2405100000000000 2000-01-01 2.4148900000000000 2001-01-01 2.5624300000000000 2002-01-01 2.5528800000000000 2003-01-01 2.6237200000000000 2004-01-01 2.2910800000000000 2005-01-01 2.2022900000000000 2006-01-01 2.2371600000000000 2007-01-01 2.3442600000000000 2008-01-01 2.2571800000000000 2009-01-01 2.4658500000000000 2010-01-01 2.4656300000000000 2011-01-01 2.2569200000000000 2012-01-01 2.2766800000000000 2013-01-01 2.1686900000000002 2014-01-01 2.0765700000000002 2015-01-01 1.9946000000000000