Year	Ratio
1971-01-01	0.458409994840622
1972-01-01	0.466140002012253
1973-01-01	0.467229992151260
1974-01-01	0.470290005207062
1975-01-01	0.473589986562729
1976-01-01	0.477389991283417
1977-01-01	0.479990005493164
1978-01-01	0.492379993200302
1979-01-01	0.480820000171661
1980-01-01	0.531040012836456
1981-01-01	0.552680015563965
1982-01-01	0.574029982089996
1983-01-01	0.603169977664948
1984-01-01	0.620589971542358
1985-01-01	0.653010010719299
1986-01-01	0.656669974327087
1987-01-01	0.636500000953674
1988-01-01	0.620150029659271
1989-01-01	0.643249988555908
1990-01-01	0.656790018081665
1991-01-01	0.665629982948303
1992-01-01	0.727699995040894
1993-01-01	0.699469983577728
1994-01-01	0.629909992218018
1995-01-01	0.599229991436005
1996-01-01	0.575110018253326
1997-01-01	0.565360009670258
1998-01-01	0.589659988880157
1999-01-01	0.613680005073547
2000-01-01	0.655990004539490
2001-01-01	0.694159984588623
2002-01-01	0.717149972915649
2003-01-01	0.733720004558563
2004-01-01	0.782260000705719
2005-01-01	0.835039973258972
2006-01-01	0.871190011501312
2007-01-01	0.888300001621246
2008-01-01	0.903230011463165
2009-01-01	0.926310002803802
2010-01-01	0.923629999160767
2011-01-01	0.920490026473999
2012-01-01	0.927980005741119
2014-01-01	0.918250024318695
2015-01-01	0.908819973468781