Year Percent 1997-01-01 0.33843600000000000 1998-01-01 0.32565700000000003 1999-01-01 0.25277100000000000 2000-01-01 0.26552300000000000 2001-01-01 0.61759500000000000 2002-01-01 0.61994399999999990 2003-01-01 0.68151700000000000 2004-01-01 0.65135200000000000 2005-01-01 0.55460700000000000 2006-01-01 0.38247200000000000 2007-01-01 0.43782900000000000 2008-01-01 0.35384899999999997 2009-01-01 0.38017800000000000 2010-01-01 0.29045900000000000 2011-01-01 0.29514900000000000 2012-01-01 0.43017900000000000 2013-01-01 0.44785600000000003 2014-01-01 0.40621100000000000 2015-01-01 0.44776600000000000