Year Percent 1990-01-01 2.0971599999999997 1991-01-01 2.0264800000000000 1992-01-01 2.0945099999999996 1993-01-01 2.2730300000000000 1994-01-01 2.3818900000000003 1995-01-01 2.4453600000000000 1996-01-01 2.5314200000000002 1997-01-01 2.6086900000000000 1998-01-01 2.6704100000000000 1999-01-01 2.8476000000000000 2000-01-01 2.8968500000000000 2001-01-01 2.8741600000000000 2002-01-01 2.9597300000000000 2003-01-01 3.0930299999999997 2004-01-01 3.1021200000000000 2005-01-01 3.2746299999999997 2006-01-01 3.2755300000000000 2007-01-01 3.1433299999999997 2008-01-01 3.1108400000000000 2009-01-01 3.4700400000000000 2010-01-01 3.5071900000000000 2011-01-01 3.2158900000000004 2012-01-01 3.2636500000000000 2013-01-01 3.2328000000000000 2014-01-01 3.2259900000000004 2015-01-01 3.0579900000000000 2016-01-01 2.8969800000000000