Year Percent 1999-01-01 0.16127600000000000 2000-01-01 0.18297100000000000 2001-01-01 0.15281800000000000 2002-01-01 0.19456600000000002 2003-01-01 0.24620900000000000 2004-01-01 0.23612800000000003 2005-01-01 0.23612800000000003 2006-01-01 0.23197399999999999 2007-01-01 0.25423000000000000 2008-01-01 0.21325900000000000 2009-01-01 0.28654400000000000 2010-01-01 0.27386200000000000 2011-01-01 0.25480000000000000 2012-01-01 0.27348600000000000 2013-01-01 0.26120800000000000 2014-01-01 0.27506600000000000 2015-01-01 0.27643100000000000 2016-01-01 0.28832100000000000