Year	Percent
1999-01-01	79.175
2000-01-01	79.825
2001-01-01	80.575
2002-01-01	79.850
2003-01-01	78.975
2004-01-01	79.800
2005-01-01	80.625
2006-01-01	82.025
2007-01-01	82.275
2008-01-01	83.975
2009-01-01	82.525
2010-01-01	80.275
2011-01-01	78.850
2012-01-01	79.100
2013-01-01	78.975
2014-01-01	78.400
2015-01-01	78.325
2016-01-01	78.500
2017-01-01	78.100