Year Percent 2003-01-01 0.57 2004-01-01 0.60 2005-01-01 0.50 2006-01-01 0.50 2007-01-01 0.48 2008-01-01 0.46 2009-01-01 0.46 2010-01-01 0.49 2011-01-01 0.52 2012-01-01 0.54 2013-01-01 0.55