Year	Ratio
1971-01-01	0.287299990653992
1972-01-01	0.327259987592697
1973-01-01	0.308290004730225
1974-01-01	0.310189992189407
1975-01-01	0.300929993391037
1976-01-01	0.310900002717972
1977-01-01	0.294860005378723
1978-01-01	0.298249989748001
1979-01-01	0.310909986495972
1980-01-01	0.316689997911453
1982-01-01	0.337040007114410
1983-01-01	0.330960005521774
1984-01-01	0.323350012302399
1985-01-01	0.313499987125397
1986-01-01	0.307810008525848
1987-01-01	0.305090010166168
1988-01-01	0.322730004787445
1989-01-01	0.309769988059998
1990-01-01	0.338450014591217
1991-01-01	0.335170000791550
1992-01-01	0.324699997901917
1994-01-01	0.340909987688065
1995-01-01	0.351929992437363
1996-01-01	0.351929992437363
1997-01-01	0.362890005111694
1999-01-01	0.399969995021820
2000-01-01	0.446440011262894
2001-01-01	0.458270013332367
2002-01-01	0.477479994297028
2003-01-01	0.493050009012222
2004-01-01	0.516340017318726
2005-01-01	0.532369971275330
2006-01-01	0.547569990158081
2007-01-01	0.530650019645691