Year Percent 1996-01-01 2.9338599999999997 1997-01-01 3.4070300000000002 1998-01-01 3.5308800000000002 1999-01-01 3.7526400000000000 2000-01-01 3.9052900000000000 2001-01-01 4.0814300000000000 2002-01-01 4.2070099999999995 2003-01-01 4.0833800000000000 2004-01-01 3.9184500000000000 2005-01-01 3.6251599999999997 2006-01-01 3.7181400000000000 2007-01-01 3.8612699999999998 2008-01-01 3.9384600000000000 2009-01-01 3.5954400000000000 2010-01-01 3.3996300000000000 2011-01-01 3.5671800000000005 2012-01-01 3.6729700000000000 2013-01-01 3.3350100000000000 2014-01-01 3.3372800000000002 2015-01-01 3.4019999999999997 2016-01-01 3.3077300000000003