Year Percent 1992-01-01 0.23272600000000002 1993-01-01 0.29611100000000000 1994-01-01 0.30511700000000000 1995-01-01 0.32444400000000000 1996-01-01 0.36898700000000000 1997-01-01 0.39442600000000000 1998-01-01 0.25794900000000000 1999-01-01 0.26307400000000000 2000-01-01 0.27148800000000000 2001-01-01 0.27339700000000000 2002-01-01 0.27185000000000000 2003-01-01 0.27305400000000000 2004-01-01 0.26643800000000000 2005-01-01 0.25666100000000003 2006-01-01 0.23563800000000001 2007-01-01 0.24055300000000002 2008-01-01 0.23001100000000002 2009-01-01 0.20633900000000000 2010-01-01 0.19509900000000000 2011-01-01 0.19930599999999998 2012-01-01 0.20195700000000000 2013-01-01 0.19881600000000002 2014-01-01 0.20883800000000002 2015-01-01 0.22728400000000000