Year	Ratio
1971-01-01	0.539590001106262
1972-01-01	0.557780027389526
1982-01-01	0.860660016536713
1983-01-01	0.818159997463226
1986-01-01	0.808130025863647
1987-01-01	0.804620027542114
1988-01-01	0.784959971904755
1989-01-01	0.820949971675873
1990-01-01	0.899800002574921
1991-01-01	0.899200022220612
1992-01-01	0.844789981842041
1998-01-01	0.812319993972778
2008-01-01	0.832910001277924
2009-01-01	0.824410021305084
2010-01-01	0.789040029048920
2011-01-01	0.621730029582977