Year	Ratio
1984-01-01	0.96609
1985-01-01	0.96507
1986-01-01	0.96448
1987-01-01	0.96489
1989-01-01	0.96456
1990-01-01	0.96585
1991-01-01	0.96753
1992-01-01	0.96845
1993-01-01	0.96648
1994-01-01	0.97010
1995-01-01	0.96799
1996-01-01	0.97049
1997-01-01	0.97269
1998-01-01	0.96657
1999-01-01	0.96130
2000-01-01	0.96538
2001-01-01	0.95686
2002-01-01	0.95395
2003-01-01	0.94753
2004-01-01	0.95197
2005-01-01	0.95516
2006-01-01	0.96041
2007-01-01	0.96212
2008-01-01	0.96726
2009-01-01	0.97538
2010-01-01	0.97301
2011-01-01	0.97117
2012-01-01	0.97957
2013-01-01	0.98363
2014-01-01	0.98492
2015-01-01	0.98639
2016-01-01	0.98799