Year	Percent
1998-01-01	29.925
1999-01-01	30.100
2000-01-01	29.900
2001-01-01	29.625
2002-01-01	29.375
2003-01-01	29.875
2004-01-01	30.550
2005-01-01	30.900
2006-01-01	30.725
2007-01-01	30.850
2008-01-01	31.050
2009-01-01	32.300
2010-01-01	32.800
2011-01-01	32.925
2012-01-01	33.700
2013-01-01	34.875
2014-01-01	35.475
2015-01-01	35.875
2016-01-01	35.900
2017-01-01	35.450