Year	Ratio
1970-01-01	0.156869992613792
1971-01-01	0.146249994635582
1972-01-01	0.132410004734993
1973-01-01	0.142299994826317
1974-01-01	0.138860002160072
1975-01-01	0.141279995441437
1976-01-01	0.151969999074936
1977-01-01	0.172639995813370
1978-01-01	0.179729998111725
1981-01-01	0.259200006723404
1982-01-01	0.446660012006760
1984-01-01	0.460500001907349
1985-01-01	0.455570012331009
1986-01-01	0.499049991369247
1988-01-01	0.492610007524490
1991-01-01	0.512220025062561
1993-01-01	0.380140006542206
1994-01-01	0.280339986085892
1995-01-01	0.373609989881516
2001-01-01	0.000000000000000
2003-01-01	0.349269986152649
2004-01-01	0.208790004253387
2005-01-01	0.325210005044937
2006-01-01	0.362430006265640
2007-01-01	0.374179989099503
2008-01-01	0.425089985132217
2009-01-01	0.481810003519058
2010-01-01	0.499599993228912
2011-01-01	0.558000028133392
2012-01-01	0.562680006027222
2013-01-01	0.558170020580292
2014-01-01	0.562520027160645
2015-01-01	0.563730001449585
2017-01-01	0.571229994297028