Year Percent 1996-01-01 0.67496099999999990 1997-01-01 0.69068300000000000 1998-01-01 0.65804800000000000 1999-01-01 0.60126000000000000 2000-01-01 0.54656500000000000 2001-01-01 0.51348800000000000 2002-01-01 0.45676200000000000 2003-01-01 0.40573400000000004 2004-01-01 0.33465500000000004 2005-01-01 0.33317600000000000 2006-01-01 0.32356999999999997 2007-01-01 0.36129100000000000 2008-01-01 0.33608299999999997 2009-01-01 0.34541600000000000 2010-01-01 0.29526800000000000 2011-01-01 0.26848400000000000 2012-01-01 0.43591000000000000 2013-01-01 0.39499600000000000 2014-01-01 0.38838000000000000 2015-01-01 0.49853000000000003