Year Percent 1996-01-01 0.23011700000000002 1997-01-01 0.25260900000000003 1998-01-01 0.23770100000000002 1999-01-01 0.23816900000000000 2000-01-01 0.25573100000000000 2001-01-01 0.25573100000000000 2002-01-01 0.25573100000000000 2003-01-01 0.25573100000000000 2004-01-01 0.25573100000000000 2005-01-01 0.25573100000000000 2006-01-01 0.25573100000000000 2007-01-01 0.25573100000000000 2008-01-01 0.25573100000000000 2009-01-01 0.25573100000000000 2010-01-01 0.25573100000000000 2011-01-01 0.25573100000000000 2012-01-01 0.25573100000000000 2013-01-01 0.56166300000000000 2014-01-01 1.99474000000000020 2015-01-01 3.31881999999999970 2016-01-01 3.17197000000000000