Year	Percent
1998-01-01	59.925
1999-01-01	60.250
2000-01-01	60.825
2001-01-01	61.300
2002-01-01	61.800
2003-01-01	62.200
2004-01-01	62.375
2005-01-01	62.100
2006-01-01	62.550
2007-01-01	62.650
2008-01-01	62.275
2009-01-01	60.800
2010-01-01	59.925
2011-01-01	59.700
2012-01-01	58.850
2013-01-01	57.325
2014-01-01	57.250
2015-01-01	58.000
2016-01-01	58.775
2017-01-01	59.425