Year	Ratio
1971-01-01	0.643490016460419
1973-01-01	0.675450026988983
1974-01-01	0.663169980049133
1975-01-01	0.664780020713806
1976-01-01	0.652949988842011
1977-01-01	0.645359992980957
1978-01-01	0.655489981174469
1979-01-01	0.647939980030060
1980-01-01	0.660920023918152
1981-01-01	0.641870021820068
1982-01-01	0.650049984455109
1983-01-01	0.628289997577667
1984-01-01	0.623000025749207
1985-01-01	0.628459990024567
1987-01-01	0.698790013790131
1988-01-01	0.667330026626587
1989-01-01	0.666570007801056
1990-01-01	0.663630008697510
1995-01-01	0.722060024738312
1999-01-01	0.804939985275269
2000-01-01	0.818019986152649
2001-01-01	0.841030001640320
2002-01-01	0.845160007476807
2003-01-01	0.846180021762848
2004-01-01	0.828090012073517
2005-01-01	0.828270018100739
2006-01-01	0.842469990253448
2007-01-01	0.870299994945526
2008-01-01	0.878979980945587
2009-01-01	0.876049995422363
2011-01-01	0.899049997329712
2012-01-01	0.898169994354248
2013-01-01	0.910189986228943
2014-01-01	0.938269972801209
2015-01-01	0.948710024356842
2016-01-01	0.967649996280670
2017-01-01	0.973980009555817