Year	Percent
1999-01-01	72.300
2000-01-01	72.975
2001-01-01	73.075
2002-01-01	73.025
2003-01-01	73.700
2004-01-01	73.625
2005-01-01	73.700
2006-01-01	74.475
2007-01-01	74.650
2008-01-01	74.550
2009-01-01	72.950
2010-01-01	72.450
2011-01-01	72.975
2012-01-01	74.625
2013-01-01	75.700
2014-01-01	79.250
2015-01-01	80.625
2016-01-01	82.200
2017-01-01	83.650