Year	Percent
1998-01-01	19.925
1999-01-01	20.100
2000-01-01	20.875
2001-01-01	21.425
2002-01-01	21.425
2003-01-01	22.050
2004-01-01	22.150
2005-01-01	21.650
2006-01-01	21.750
2007-01-01	21.875
2008-01-01	21.850
2009-01-01	21.500
2010-01-01	21.400
2011-01-01	21.325
2012-01-01	20.550
2013-01-01	19.525
2014-01-01	18.775
2015-01-01	18.625
2016-01-01	17.825
2017-01-01	17.125