Year	Percent
1998-01-01	26.325
1999-01-01	26.575
2000-01-01	26.300
2001-01-01	25.800
2002-01-01	25.575
2003-01-01	26.075
2004-01-01	26.650
2005-01-01	26.800
2006-01-01	26.475
2007-01-01	26.525
2008-01-01	26.625
2009-01-01	27.700
2010-01-01	28.200
2011-01-01	28.025
2012-01-01	28.750
2013-01-01	29.750
2014-01-01	30.125
2015-01-01	30.375
2016-01-01	30.125
2017-01-01	29.575