Year	Percent
1999-01-01	30.500
2000-01-01	31.150
2001-01-01	31.650
2002-01-01	31.775
2003-01-01	31.475
2004-01-01	33.875
2005-01-01	33.625
2006-01-01	33.275
2007-01-01	32.400
2008-01-01	32.525
2009-01-01	32.675
2010-01-01	32.900
2011-01-01	33.125
2012-01-01	33.075
2013-01-01	33.050
2014-01-01	33.575
2015-01-01	33.600
2016-01-01	33.200
2017-01-01	33.175