Year	Percent
1998-01-01	60.800
1999-01-01	63.425
2000-01-01	64.225
2001-01-01	65.400
2002-01-01	66.200
2003-01-01	65.700
2004-01-01	65.550
2005-01-01	66.550
2006-01-01	67.275
2007-01-01	68.475
2008-01-01	68.975
2009-01-01	67.900
2010-01-01	66.925
2011-01-01	67.425
2012-01-01	68.175
2013-01-01	67.825
2014-01-01	67.950
2015-01-01	67.725
2016-01-01	67.625
2017-01-01	68.525