Year	Ratio
1971-01-01	0.742429971694946
1972-01-01	0.689119994640350
1973-01-01	0.708130002021790
1986-01-01	0.800419986248016
1987-01-01	0.767310023307800
1988-01-01	0.772239983081818
1989-01-01	0.784990012645721
1994-01-01	0.832629978656769
1995-01-01	0.815320014953613
1997-01-01	0.830439984798431
1998-01-01	0.842060029506683
1999-01-01	0.869140028953552
2000-01-01	0.877569973468781
2001-01-01	0.894990026950836
2002-01-01	0.902610003948212
2003-01-01	0.911180019378662
2004-01-01	0.920279979705811
2005-01-01	0.929120004177094
2006-01-01	0.933950006961823
2007-01-01	0.933139979839325
2008-01-01	0.937940001487732
2009-01-01	0.934889972209930
2010-01-01	0.943549990653992
2011-01-01	0.932860016822815
2012-01-01	0.932340025901794
2013-01-01	0.909889996051788
2014-01-01	0.946200013160706
2015-01-01	0.992850005626678
2016-01-01	0.974690020084381