Year	Ratio
1971-01-01	0.834330022335052
1972-01-01	0.843299984931946
1973-01-01	0.854979991912842
1974-01-01	0.869050025939941
1975-01-01	0.883530020713806
1976-01-01	0.893580019474030
1977-01-01	0.905239999294281
1978-01-01	0.923039972782135
1979-01-01	0.938289999961853
1980-01-01	0.953599989414215
1981-01-01	0.965889990329742
1982-01-01	0.977460026741028
1983-01-01	0.982400000095367
1984-01-01	0.985419988632202
1985-01-01	0.988240003585815
1986-01-01	0.989769995212555
1987-01-01	0.991029977798462
1988-01-01	0.991129994392395
1989-01-01	0.992129981517792
1990-01-01	1.005300045013430
1991-01-01	0.997690021991730
1992-01-01	0.998749971389771
1993-01-01	0.998260021209717
1994-01-01	0.997919976711273
1995-01-01	0.997009992599487
1996-01-01	1.000460028648380
1997-01-01	0.999920010566711
1998-01-01	0.995930016040802
1999-01-01	0.994610011577606
2000-01-01	0.962650001049042
2001-01-01	0.977959990501404
2002-01-01	0.966310024261475
2003-01-01	0.974969983100891
2004-01-01	0.994490027427673
2005-01-01	0.993269979953766
2006-01-01	0.991750001907349
2007-01-01	0.989719986915588
2008-01-01	0.988990008831024
2009-01-01	0.989910006523132
2010-01-01	0.986190021038055
2011-01-01	0.981369972229004
2012-01-01	0.980549991130829
2013-01-01	0.980690002441406
2014-01-01	0.977980017662048
2015-01-01	0.977280020713806