Year	Ratio
1970-01-01	0.596870005130768
1971-01-01	0.634850025177002
1972-01-01	0.653970003128052
1973-01-01	0.679059982299805
1976-01-01	0.686070024967194
1977-01-01	0.758249998092651
1978-01-01	0.783569991588593
1979-01-01	0.778050005435944
1980-01-01	0.789979994297028
1981-01-01	0.797160029411316
1982-01-01	0.788489997386932
1983-01-01	0.776310026645660
1984-01-01	0.778670012950897
1985-01-01	0.810880005359650
1986-01-01	0.820089995861053
1987-01-01	0.823440015316010
1988-01-01	0.760299980640411
1989-01-01	0.844990015029907
1990-01-01	0.786000013351440
1991-01-01	0.806140005588531
1992-01-01	0.816770017147064
1993-01-01	0.804090023040771
1994-01-01	0.815219998359680
1995-01-01	0.831070005893707
1996-01-01	0.856329977512360
1999-01-01	0.806930005550385
2000-01-01	0.810350000858307
2001-01-01	0.826590001583099
2002-01-01	0.825590014457703
2003-01-01	0.831879973411560
2004-01-01	0.837809979915619
2005-01-01	0.843219995498657
2006-01-01	0.859790027141571
2007-01-01	0.882279992103577
2008-01-01	0.888090014457703
2009-01-01	0.896229982376099
2010-01-01	0.908370018005371
2011-01-01	0.932569980621338
2012-01-01	0.973940014839172
2013-01-01	0.974680006504059