Year	Percent
1998-01-01	34.575
1999-01-01	34.975
2000-01-01	35.275
2001-01-01	35.925
2002-01-01	35.925
2003-01-01	35.650
2004-01-01	35.650
2005-01-01	35.700
2006-01-01	35.650
2007-01-01	35.850
2008-01-01	35.825
2009-01-01	35.975
2010-01-01	36.425
2011-01-01	37.825
2012-01-01	38.725
2013-01-01	39.100
2014-01-01	39.875
2015-01-01	40.200
2016-01-01	40.175
2017-01-01	40.025