Year	Ratio
1971-01-01	0.398600012063980
1972-01-01	0.391070008277893
1973-01-01	0.425399988889694
1974-01-01	0.438340008258820
1975-01-01	0.454160004854202
1976-01-01	0.472849994897842
1977-01-01	0.422490000724792
1979-01-01	0.496989995241165
1980-01-01	0.578689992427826
1981-01-01	0.515240013599396
1982-01-01	0.553939998149872
1983-01-01	0.517270028591156
1984-01-01	0.532729983329773
1985-01-01	0.550010025501251
1986-01-01	0.517520010471344
1994-01-01	0.556460022926331
1999-01-01	0.617749989032745
2000-01-01	0.656229972839355
2001-01-01	0.662469983100891
2003-01-01	0.683629989624023
2004-01-01	0.695200026035309
2005-01-01	0.707549989223480
2006-01-01	0.724259972572327
2007-01-01	0.732739984989166
2008-01-01	0.741750001907349
2009-01-01	0.744660019874573
2010-01-01	0.763589978218079
2011-01-01	0.780130028724670
2012-01-01	0.811349987983704
2013-01-01	0.846459984779358
2014-01-01	0.873290002346039
2015-01-01	0.921689987182617
2016-01-01	0.950999975204468