Year Percent 2001-01-01 7.9398800000000005 2002-01-01 4.2018800000000000 2003-01-01 3.1291700000000002 2004-01-01 2.9650700000000000 2005-01-01 3.5202900000000000 2006-01-01 3.2274900000000000 2007-01-01 3.1966200000000002 2008-01-01 3.5038800000000000 2009-01-01 3.5527300000000004 2010-01-01 3.1508599999999998 2011-01-01 3.1792900000000000 2012-01-01 3.0212400000000000 2013-01-01 2.9033500000000000 2014-01-01 2.7877400000000003 2015-01-01 2.6250400000000003 2016-01-01 2.3721900000000002