Year Percent 2003-01-01 3.87304397420484 2004-01-01 4.05858418647610 2005-01-01 4.07123876558011 2006-01-01 4.04498373944358 2007-01-01 3.67448227350336 2008-01-01 3.39348641481485 2009-01-01 4.20815582579854 2010-01-01 4.27462096075152 2011-01-01 4.20890604947348 2012-01-01 4.52586230325935 2013-01-01 4.52293566360468