Year Percent 2003-01-01 2.91 2004-01-01 2.91 2005-01-01 2.78 2006-01-01 2.55 2007-01-01 2.37 2008-01-01 2.16 2009-01-01 2.36 2010-01-01 2.18 2011-01-01 2.08 2012-01-01 2.28 2013-01-01 2.42 2014-01-01 2.47 2015-01-01 4.64 2016-01-01 4.72