Year Percent 1990-01-01 2.3494300000000000 1991-01-01 2.4032299999999998 1992-01-01 2.4283300000000000 1993-01-01 2.4549200000000000 1994-01-01 2.4381400000000000 1995-01-01 2.5328800000000000 1996-01-01 2.4978100000000000 1997-01-01 2.4119099999999998 1998-01-01 2.3461900000000000 1999-01-01 2.2211400000000000 2000-01-01 2.1548500000000000 2001-01-01 2.3143000000000000 2002-01-01 2.5927300000000000 2003-01-01 2.8586300000000000 2004-01-01 2.8818000000000000 2005-01-01 2.7275300000000000 2006-01-01 2.6899700000000000 2007-01-01 2.3324100000000000 2008-01-01 2.2435200000000000 2009-01-01 2.4119599999999997 2010-01-01 2.3899600000000000 2011-01-01 2.4900300000000000 2012-01-01 2.5395700000000000 2013-01-01 2.6004400000000003 2014-01-01 2.5799400000000000 2015-01-01 2.6620400000000000 2016-01-01 2.6964900000000003