Year	Ratio
1971-01-01	0.855989992618561
1972-01-01	0.883650004863739
1973-01-01	0.868570029735565
1974-01-01	0.881259977817535
1976-01-01	0.895619988441467
1977-01-01	0.886879980564117
1978-01-01	0.893029987812042
1981-01-01	0.914269983768463
1982-01-01	0.911029994487762
1983-01-01	0.912169992923737
1984-01-01	0.902570009231567
1985-01-01	0.907930016517639
1986-01-01	0.921060025691986
1987-01-01	0.913200020790100
1988-01-01	0.916270017623901
1989-01-01	0.920960009098053
1990-01-01	0.925729990005493
1991-01-01	0.940429985523224
1992-01-01	0.939800024032593
1993-01-01	0.937590003013611
1994-01-01	0.944670021533966
1995-01-01	0.940360009670258
1999-01-01	0.969619989395142
2000-01-01	0.976170003414154
2001-01-01	0.979260027408600
2002-01-01	0.990520000457764
2003-01-01	0.992910027503967
2004-01-01	0.994930028915405
2005-01-01	1.001940011978150
2006-01-01	0.990930020809174
2008-01-01	0.994849979877472
2009-01-01	0.984499990940094
2010-01-01	0.991819977760315
2014-01-01	0.972999989986420
2017-01-01	0.969640016555786