Year	Percent
1999-01-01	57.500
2000-01-01	57.650
2001-01-01	58.025
2002-01-01	57.425
2003-01-01	56.550
2004-01-01	58.975
2005-01-01	59.225
2006-01-01	59.300
2007-01-01	59.700
2008-01-01	59.500
2009-01-01	59.425
2010-01-01	59.150
2011-01-01	57.925
2012-01-01	57.525
2013-01-01	57.225
2014-01-01	57.650
2015-01-01	57.300
2016-01-01	56.600
2017-01-01	58.450