Year	Ratio
1970-01-01	0.97359
1971-01-01	0.97322
1972-01-01	0.97489
1973-01-01	0.98156
1974-01-01	0.97578
1975-01-01	0.97733
1976-01-01	0.98374
1977-01-01	0.97664
1978-01-01	0.97747
1979-01-01	0.97629
1980-01-01	0.97771
1981-01-01	0.97804
1982-01-01	0.98071
1983-01-01	0.98206
1984-01-01	0.98200
1985-01-01	0.98307
1986-01-01	0.98330
1987-01-01	0.98405
1988-01-01	0.98276
1989-01-01	0.98443
1990-01-01	0.98559
1991-01-01	0.98672
1992-01-01	0.98799
1993-01-01	0.98834
1994-01-01	0.98636
1995-01-01	0.98419
1996-01-01	0.98299
1997-01-01	0.98191
1998-01-01	0.98158
1999-01-01	0.98153
2000-01-01	0.98203
2001-01-01	0.98355
2002-01-01	0.98364
2003-01-01	0.98573
2004-01-01	0.98655
2005-01-01	0.98624
2006-01-01	0.98826
2007-01-01	0.98926
2008-01-01	0.98964
2009-01-01	0.99186
2010-01-01	0.99331
2011-01-01	0.99510
2012-01-01	0.99562
2013-01-01	0.99783
2014-01-01	0.99871
2015-01-01	0.99881
2016-01-01	0.99885