Year	Percent
1998-01-01	73.37109375
1999-01-01	66.69305420
2000-01-01	67.79338837
2001-01-01	63.13239670
2002-01-01	58.14595413
2003-01-01	55.40757751
2004-01-01	57.14881134
2005-01-01	55.56048584
2006-01-01	67.34988403
2007-01-01	66.94323730
2008-01-01	67.78878021
2009-01-01	74.32810974
2010-01-01	66.94737244
2011-01-01	60.70322800
2012-01-01	64.63069153
2013-01-01	66.16506195