Year	Percent
1998-01-01	44.775
1999-01-01	44.700
2000-01-01	47.300
2001-01-01	51.300
2002-01-01	52.975
2003-01-01	55.300
2004-01-01	55.600
2005-01-01	56.900
2006-01-01	58.850
2007-01-01	59.125
2008-01-01	60.600
2009-01-01	58.700
2010-01-01	60.075
2011-01-01	61.375
2012-01-01	61.625
2013-01-01	61.500
2014-01-01	61.900
2015-01-01	63.200
2016-01-01	65.125
2017-01-01	67.525