Year	Percent
1999-01-01	39.700
2000-01-01	39.900
2001-01-01	39.475
2002-01-01	39.900
2003-01-01	40.200
2004-01-01	39.350
2005-01-01	39.600
2006-01-01	39.075
2007-01-01	39.350
2008-01-01	39.050
2009-01-01	39.375
2010-01-01	40.225
2011-01-01	40.400
2012-01-01	40.925
2013-01-01	41.425
2014-01-01	41.975
2015-01-01	42.200
2016-01-01	40.550
2017-01-01	41.750