Year Percent 1996-01-01 2.7865500000000000 1997-01-01 2.2728700000000000 1998-01-01 2.8541700000000000 1999-01-01 3.2174500000000000 2000-01-01 3.2594600000000000 2001-01-01 3.3503800000000004 2002-01-01 3.3479099999999997 2003-01-01 3.6986700000000000 2004-01-01 3.5815500000000000 2005-01-01 3.6474000000000000 2006-01-01 4.0728700000000000 2007-01-01 4.2026600000000000 2008-01-01 4.0484200000000000 2009-01-01 3.7220199999999997 2010-01-01 3.2627200000000003 2011-01-01 3.4733699999999996 2012-01-01 3.3938500000000000 2013-01-01 3.1820900000000000 2014-01-01 3.8621199999999996 2015-01-01 3.9252599999999997 2016-01-01 3.6619800000000002