Year	Ratio
1970-01-01	0.80214
1971-01-01	0.80107
1972-01-01	0.80058
1973-01-01	0.79829
1974-01-01	0.79438
1975-01-01	0.82348
1976-01-01	0.84052
1977-01-01	0.84453
1978-01-01	0.84424
1979-01-01	0.84459
1980-01-01	0.84728
1981-01-01	0.84817
1982-01-01	0.84632
1983-01-01	0.84312
1984-01-01	0.84741
1985-01-01	0.85197
1986-01-01	0.86441
1987-01-01	0.86940
1988-01-01	0.87222
1989-01-01	0.87399
1990-01-01	0.87894
1991-01-01	0.88685
1992-01-01	0.89295
1993-01-01	0.89827
1994-01-01	0.90211
1995-01-01	0.90418
1996-01-01	0.90649
1997-01-01	0.91197
1998-01-01	0.91480
1999-01-01	0.91963
2000-01-01	0.92082
2001-01-01	0.92607
2002-01-01	0.92803
2003-01-01	0.94818
2004-01-01	0.94947
2005-01-01	0.95217
2006-01-01	0.95627
2007-01-01	0.95858
2008-01-01	0.96558
2009-01-01	0.97056
2010-01-01	0.97290
2011-01-01	0.97558
2012-01-01	0.97915
2013-01-01	0.99495
2014-01-01	0.99478
2015-01-01	0.99717
2016-01-01	1.00482