Year Percent 1990-01-01 0.16531500000000002 1991-01-01 0.24098100000000000 1992-01-01 0.28914500000000000 1993-01-01 0.25328600000000000 1994-01-01 0.15557600000000000 1995-01-01 0.15975300000000000 1996-01-01 0.14179800000000000 1997-01-01 0.14166199999999998 1998-01-01 0.16691900000000000 1999-01-01 0.18748800000000002 2000-01-01 0.11267100000000001 2001-01-01 0.16529300000000000 2002-01-01 0.15471500000000002 2003-01-01 0.15924100000000002 2004-01-01 0.14905000000000000 2005-01-01 0.12866600000000000 2006-01-01 0.15049900000000000 2007-01-01 0.16274300000000000 2008-01-01 0.15616300000000002 2009-01-01 0.21099000000000000 2010-01-01 0.17313699999999999 2011-01-01 0.17666700000000002 2012-01-01 0.17338199999999998 2013-01-01 0.20143000000000000 2014-01-01 0.19660000000000000 2015-01-01 0.20048200000000000