Year Percent 1990-01-01 0.16901500000000000 1991-01-01 0.16510500000000000 1992-01-01 0.18102100000000002 1993-01-01 0.19412300000000000 1994-01-01 0.19995100000000000 1995-01-01 0.20987800000000000 1996-01-01 0.20224400000000000 1997-01-01 0.21259099999999997 1998-01-01 0.21237800000000000 1999-01-01 0.20002600000000000 2000-01-01 0.19938900000000000 2001-01-01 0.22167800000000001 2002-01-01 0.21302900000000000 2003-01-01 0.22128400000000000 2004-01-01 0.18472500000000000 2005-01-01 0.19150200000000000 2006-01-01 0.19023400000000000 2007-01-01 0.20051000000000000 2008-01-01 0.20339200000000002 2009-01-01 0.21672900000000000 2010-01-01 0.22352199999999997 2011-01-01 0.27350200000000000 2012-01-01 0.26681900000000003 2013-01-01 0.27131400000000000 2014-01-01 0.28454900000000000 2015-01-01 0.26973800000000003 2016-01-01 0.27723900000000000