Year	Ratio
1971-01-01	0.301600009202957
1973-01-01	0.308759987354279
1974-01-01	0.322609990835190
1975-01-01	0.354820013046265
1976-01-01	0.369769990444183
1977-01-01	0.405039995908737
1978-01-01	0.451660007238388
1979-01-01	0.404390007257462
1980-01-01	0.402889996767044
1981-01-01	0.416460007429123
1983-01-01	0.428499996662140
1984-01-01	0.423869997262955
1985-01-01	0.414099991321564
1986-01-01	0.406630009412766
1987-01-01	0.423559993505478
1988-01-01	0.413540005683899
1989-01-01	0.409929990768433
1990-01-01	0.474319994449615
1991-01-01	0.497029989957809
1992-01-01	0.526149988174438
1993-01-01	0.525820016860962
1994-01-01	0.536050021648407
1995-01-01	0.536520004272461
1996-01-01	0.607659995555878
2008-01-01	0.930410027503967
2009-01-01	0.957880020141602
2010-01-01	0.951409995555878