Year	Percent
1999-01-01	19.450
2000-01-01	19.925
2001-01-01	20.550
2002-01-01	20.425
2003-01-01	20.125
2004-01-01	22.650
2005-01-01	21.975
2006-01-01	21.125
2007-01-01	20.050
2008-01-01	20.000
2009-01-01	20.025
2010-01-01	19.950
2011-01-01	20.100
2012-01-01	19.750
2013-01-01	19.600
2014-01-01	20.000
2015-01-01	19.900
2016-01-01	19.325
2017-01-01	18.975