Year	Percent
1998-01-01	82.07054901
1999-01-01	84.58887482
2000-01-01	84.53498840
2001-01-01	84.52908325
2002-01-01	85.53409576
2003-01-01	81.81079102
2004-01-01	80.31211090
2005-01-01	79.67311859
2006-01-01	83.99553680
2007-01-01	87.74040222
2008-01-01	88.95788574
2009-01-01	91.57270813
2010-01-01	85.33151245
2011-01-01	80.26805878
2012-01-01	84.69477081
2013-01-01	87.37141418