Year	Percent
1999-01-01	67.150
2000-01-01	68.175
2001-01-01	68.250
2002-01-01	67.575
2003-01-01	68.600
2004-01-01	67.225
2005-01-01	67.700
2006-01-01	68.100
2007-01-01	68.450
2008-01-01	69.250
2009-01-01	70.075
2010-01-01	70.225
2011-01-01	70.225
2012-01-01	72.100
2013-01-01	71.750
2014-01-01	71.925
2015-01-01	72.875
2016-01-01	73.850
2017-01-01	74.550