Year	Percent
1997-01-01	87.55817
1998-01-01	61.35328
1999-01-01	59.10394
2000-01-01	58.02800
2001-01-01	56.93715
2002-01-01	54.85073
2003-01-01	56.81146
2004-01-01	58.83256
2005-01-01	57.20055
2006-01-01	51.05634
2007-01-01	48.59563
2008-01-01	49.73265
2009-01-01	52.69759
2010-01-01	59.08630