Year	Percent
1998-01-01	34.025
1999-01-01	33.975
2000-01-01	33.775
2001-01-01	33.825
2002-01-01	33.575
2003-01-01	33.250
2004-01-01	33.400
2005-01-01	33.800
2006-01-01	33.850
2007-01-01	34.125
2008-01-01	34.075
2009-01-01	34.825
2010-01-01	35.200
2011-01-01	35.425
2012-01-01	34.725
2013-01-01	35.225
2014-01-01	35.025
2015-01-01	34.625
2016-01-01	34.050
2017-01-01	33.725