Year	Percent
1998-01-01	29.500
1999-01-01	29.800
2000-01-01	30.550
2001-01-01	30.975
2002-01-01	31.025
2003-01-01	31.575
2004-01-01	31.675
2005-01-01	31.300
2006-01-01	31.475
2007-01-01	31.675
2008-01-01	31.800
2009-01-01	31.700
2010-01-01	31.950
2011-01-01	32.475
2012-01-01	32.300
2013-01-01	31.950
2014-01-01	31.800
2015-01-01	31.975
2016-01-01	31.625
2017-01-01	31.450