Year	Percent
1999-01-01	54.525
2000-01-01	55.725
2001-01-01	57.975
2002-01-01	57.875
2003-01-01	60.200
2004-01-01	60.300
2005-01-01	59.500
2006-01-01	60.700
2007-01-01	58.950
2008-01-01	58.375
2009-01-01	58.250
2010-01-01	58.450
2011-01-01	59.550
2012-01-01	60.850
2013-01-01	61.625
2014-01-01	63.225
2015-01-01	64.675
2016-01-01	67.750
2017-01-01	68.950