Year Percent 1990-01-01 0.45819899999999997 1991-01-01 0.45204399999999995 1992-01-01 0.42731499999999994 1993-01-01 0.48664600000000000 1994-01-01 0.40164800000000000 1995-01-01 0.33442000000000000 1996-01-01 0.34261300000000000 1997-01-01 0.38035300000000000 1998-01-01 0.35104300000000000 1999-01-01 0.32865100000000000 2000-01-01 0.27215900000000004 2001-01-01 0.27367900000000000 2002-01-01 0.33481700000000003 2003-01-01 0.39623900000000000 2004-01-01 0.37908100000000000 2005-01-01 0.42295200000000005 2006-01-01 0.43712300000000000 2007-01-01 0.44222200000000000 2008-01-01 0.40694200000000000 2009-01-01 0.32411599999999996 2010-01-01 0.26930600000000000 2011-01-01 0.23152399999999998 2012-01-01 0.22072600000000003 2013-01-01 0.20666100000000000 2014-01-01 0.21849800000000000 2015-01-01 0.22298300000000000 2016-01-01 0.21888700000000000