Year	Ratio
1973-01-01	0.77073
1974-01-01	0.76616
1975-01-01	0.84110
1976-01-01	0.88011
1977-01-01	0.88562
1978-01-01	0.87926
1979-01-01	0.87004
1980-01-01	0.87004
1981-01-01	0.86499
1982-01-01	0.85746
1983-01-01	0.85874
1984-01-01	0.86355
1985-01-01	0.86683
1986-01-01	0.88870
1987-01-01	0.89807
1988-01-01	0.90557
1989-01-01	0.91458
1990-01-01	0.92123
1991-01-01	0.93336
1992-01-01	0.94248
1993-01-01	0.94318
1994-01-01	0.95010
1995-01-01	0.95426
1996-01-01	0.96002
1997-01-01	0.96707
1998-01-01	0.96879
1999-01-01	0.97499
2000-01-01	0.98008
2001-01-01	0.98593
2002-01-01	0.98422
2003-01-01	0.98573
2004-01-01	0.99026
2005-01-01	0.98825
2006-01-01	0.98569
2007-01-01	0.98239
2008-01-01	0.98398
2009-01-01	0.98318
2010-01-01	0.99238
2011-01-01	0.99471
2012-01-01	0.99154
2013-01-01	0.99393
2014-01-01	0.99331
2015-01-01	0.99088
2016-01-01	0.99098