Year Percent 1991-01-01 0.19079800000000000 1992-01-01 0.16077200000000000 1993-01-01 0.23338000000000003 1994-01-01 0.26557600000000003 1995-01-01 0.27619099999999996 1996-01-01 0.31375500000000000 1997-01-01 0.35821800000000000 1998-01-01 0.46544900000000000 1999-01-01 0.46918200000000000 2000-01-01 0.39182300000000000 2001-01-01 0.38524899999999995 2002-01-01 0.39565200000000000 2003-01-01 0.40856600000000000 2004-01-01 0.37662500000000000 2005-01-01 0.27352500000000000 2006-01-01 0.33301500000000000 2007-01-01 0.47428700000000000 2008-01-01 0.47686999999999996 2009-01-01 0.59886900000000000 2010-01-01 0.46952400000000000 2011-01-01 0.41154700000000005 2012-01-01 0.40768100000000000 2013-01-01 0.41805500000000000 2014-01-01 0.39853700000000000 2015-01-01 0.39535700000000000