Year	Ratio
1971-01-01	0.346230000257492
1976-01-01	0.197579994797707
1993-01-01	0.442739993333817
1994-01-01	0.530470013618469
1999-01-01	0.377799987792969
2000-01-01	0.447030007839203
2002-01-01	0.588469982147217
2005-01-01	0.735790014266968