Year	Ratio
1971-01-01	0.259710013866425
1972-01-01	0.274379998445511
1973-01-01	0.301030009984970
1974-01-01	0.307009994983673
1975-01-01	0.324939996004105
1976-01-01	0.320859998464584
1977-01-01	0.331679999828339
1978-01-01	0.336679995059967
1979-01-01	0.373760014772415
1980-01-01	0.365610003471375
1981-01-01	0.367020010948181
1982-01-01	0.369019985198975
1983-01-01	0.351539999246597
1984-01-01	0.352809995412827
1985-01-01	0.363169997930527
1986-01-01	0.392729997634888
1987-01-01	0.402300000190735
1988-01-01	0.411760002374649
1989-01-01	0.417789995670319
1990-01-01	0.417430013418198
1991-01-01	0.477679997682571
1992-01-01	0.501590013504028
2006-01-01	0.776660025119781
2007-01-01	0.759739995002747
2008-01-01	0.760029971599579
2009-01-01	0.793349981307983
2010-01-01	0.771809995174408
2011-01-01	0.752049982547760
2012-01-01	0.734529972076416
2013-01-01	0.731019973754883
2014-01-01	0.790589988231659
2015-01-01	0.792760014533997
2016-01-01	0.810620009899139