Year	Ratio
1971-01-01	0.520770013332367
1972-01-01	0.531570017337799
1973-01-01	0.540790021419525
1974-01-01	0.551060020923615
1975-01-01	0.539129972457886
1976-01-01	0.563329994678497
1977-01-01	0.579280018806458
1978-01-01	0.581920027732849
1979-01-01	0.597989976406097
1980-01-01	0.600149989128113
1981-01-01	0.621299982070923
1982-01-01	0.636070013046265
1983-01-01	0.649169981479645
1984-01-01	0.661350011825562
1985-01-01	0.675469994544983
1986-01-01	0.693080008029938
1987-01-01	0.705179989337921
1988-01-01	0.723829984664917
1989-01-01	0.738690018653870
1990-01-01	0.776560008525848
1991-01-01	0.801819980144501
1992-01-01	0.847970008850098
1993-01-01	0.855400025844574
1994-01-01	0.845950007438660
1995-01-01	0.882629990577698
1996-01-01	0.879589974880219
1997-01-01	0.875020027160645
1999-01-01	0.923160016536713
2000-01-01	0.934729993343353
2001-01-01	0.943279981613159
2003-01-01	0.944289982318878
2004-01-01	0.947880029678345
2009-01-01	0.990819990634918
2010-01-01	0.972880005836487
2011-01-01	0.988829970359802
2012-01-01	0.984409987926483
2013-01-01	0.978739976882935
2014-01-01	0.994650006294250
2016-01-01	0.982580006122589