Year Percent 1990-01-01 0.28848100000000000 1991-01-01 0.48767400000000000 1992-01-01 0.55860700000000000 1993-01-01 0.57210900000000000 1994-01-01 0.52687100000000000 1995-01-01 0.52480600000000000 1996-01-01 0.45851700000000000 1997-01-01 0.49018100000000003 1998-01-01 0.48657900000000000 1999-01-01 0.44919600000000000 2000-01-01 0.41559900000000000 2001-01-01 0.46551600000000000 2002-01-01 0.49678500000000003 2003-01-01 0.48228300000000000 2004-01-01 0.48911099999999996 2005-01-01 0.48911099999999996 2006-01-01 0.42008800000000000 2007-01-01 0.43195100000000003 2008-01-01 0.47777900000000000 2009-01-01 0.52060200000000000 2010-01-01 0.54419400000000000 2011-01-01 0.46906700000000000 2012-01-01 0.31926400000000000 2013-01-01 0.19346200000000000 2014-01-01 0.18764300000000000 2015-01-01 0.13635700000000000