Year	Percent
1991-01-01	67.4003921654495
1992-01-01	67.4146106597104
1993-01-01	67.2477337790399
1994-01-01	67.1912154515289
1995-01-01	67.1425844230801
1996-01-01	66.9952619975095
1997-01-01	66.9749574448253
1998-01-01	66.8595155903752
1999-01-01	66.6724983833713
2000-01-01	66.7130994032493
2001-01-01	66.8431942704175
2002-01-01	67.0951781505914
2003-01-01	67.2457214567111
2004-01-01	67.3561669374339
2005-01-01	67.5716208089181
2006-01-01	67.6465064354564
2007-01-01	67.6710923784028
2008-01-01	67.7151584337866
2009-01-01	67.7476106383798
2010-01-01	67.6528947426819
2011-01-01	67.7383667770011
2012-01-01	67.8008133078263
2013-01-01	67.9425025533949
2014-01-01	67.9287884316949
2015-01-01	67.7733899949780
2016-01-01	67.7008570328392
2017-01-01	67.7310510967965