Year	Percent
1997-01-01	100.00000
1998-01-01	84.82962
1999-01-01	82.71774
2000-01-01	80.49228
2001-01-01	79.78625
2002-01-01	75.03302
2003-01-01	80.25780
2004-01-01	82.60842
2005-01-01	78.88367
2006-01-01	73.91335
2007-01-01	68.51763
2008-01-01	67.66364
2009-01-01	71.03296
2010-01-01	80.46726