Year Percent 1992-01-01 0.15274200000000002 1993-01-01 0.18497200000000000 1994-01-01 0.21053500000000000 1995-01-01 0.21374800000000000 1996-01-01 0.21402800000000002 1997-01-01 0.24389899999999998 1998-01-01 0.29712900000000000 1999-01-01 0.28952700000000000 2000-01-01 0.26690200000000000 2001-01-01 0.16830599999999998 2002-01-01 0.17390000000000000 2003-01-01 0.18059200000000000 2004-01-01 0.19210000000000000 2005-01-01 0.18166000000000000 2006-01-01 0.20245200000000000 2007-01-01 0.27966399999999997 2008-01-01 0.22956200000000000 2009-01-01 0.35144899999999996 2010-01-01 0.38380400000000000 2011-01-01 0.36663600000000000 2012-01-01 0.43450200000000005 2013-01-01 0.49443400000000004 2014-01-01 0.58934600000000000 2015-01-01 0.69775800000000000