Year	Ratio
1970-01-01	0.61642
1971-01-01	0.61560
1972-01-01	0.62316
1973-01-01	0.63151
1974-01-01	0.63715
1975-01-01	0.64929
1976-01-01	0.66217
1977-01-01	0.67612
1978-01-01	0.68916
1979-01-01	0.71571
1980-01-01	0.72979
1981-01-01	0.74310
1982-01-01	0.75231
1983-01-01	0.76182
1984-01-01	0.77495
1985-01-01	0.78732
1986-01-01	0.79983
1987-01-01	0.80838
1988-01-01	0.81178
1989-01-01	0.82642
1990-01-01	0.83747
1991-01-01	0.84244
1992-01-01	0.85503
1993-01-01	0.86235
1994-01-01	0.86476
1995-01-01	0.87283
1996-01-01	0.84767
1997-01-01	0.87273
1998-01-01	0.87871
1999-01-01	0.88643
2000-01-01	0.89468
2001-01-01	0.90462
2002-01-01	0.91093
2003-01-01	0.91665
2004-01-01	0.92151
2005-01-01	0.92390
2006-01-01	0.92627
2007-01-01	0.93172
2008-01-01	0.93599
2009-01-01	0.93833
2010-01-01	0.94074
2011-01-01	0.93615
2012-01-01	0.94652
2013-01-01	0.95457
2014-01-01	0.96092
2015-01-01	0.96589
2016-01-01	0.96412