Year Percent 1998-01-01 23.580300000000000 1999-01-01 23.668600000000000 2000-01-01 27.700000000000000 2001-01-01 24.100000000000000 2002-01-01 22.781999999999996 2003-01-01 21.297600000000000 2004-01-01 20.665500000000000 2005-01-01 19.436900000000000 2006-01-01 22.230200000000000 2007-01-01 31.840500000000000 2008-01-01 25.187500000000000 2009-01-01 28.094800000000000 2010-01-01 30.093600000000000 2011-01-01 29.864800000000000 2012-01-01 31.472800000000000 2013-01-01 25.891000000000000 2014-01-01 27.621400000000000 2015-01-01 36.661700000000000 2016-01-01 42.594200000000000