Year	Ratio
1981-01-01	0.976469993591309
1986-01-01	0.972299993038177
1991-01-01	1.000710010528560
1992-01-01	0.977219998836517
1993-01-01	0.951460003852844
1994-01-01	0.930249989032745
1995-01-01	1.020499944686890
1996-01-01	1.041540026664730
1997-01-01	1.078889966011050