Year	Percent
1998-01-01	38.875
1999-01-01	41.825
2000-01-01	44.500
2001-01-01	49.325
2002-01-01	51.225
2003-01-01	52.225
2004-01-01	54.275
2005-01-01	56.375
2006-01-01	58.175
2007-01-01	58.425
2008-01-01	58.800
2009-01-01	59.575
2010-01-01	60.300
2011-01-01	60.400
2012-01-01	62.925
2013-01-01	64.275
2014-01-01	65.550
2015-01-01	67.175
2016-01-01	67.650
2017-01-01	68.150