Year	Percent
1997-01-01	100.0000
1998-01-01	96.0352
1999-01-01	86.7449
2000-01-01	86.6729
2001-01-01	94.6815
2002-01-01	82.3303
2003-01-01	84.8555
2004-01-01	82.5748
2005-01-01	83.1334
2006-01-01	81.5844
2007-01-01	84.5292
2008-01-01	83.0947
2009-01-01	82.1135
2010-01-01	83.5641
2011-01-01	84.8909
2012-01-01	84.2827
2013-01-01	81.9039
2014-01-01	81.2191
2015-01-01	78.7994
2016-01-01	85.3573