Year	Ratio
1971-01-01	0.478810012340546
1972-01-01	0.486790001392365
1973-01-01	0.498510003089905
1974-01-01	0.520860016345978
1975-01-01	0.507849991321564
1976-01-01	0.552919983863831
1977-01-01	0.541800022125244
1978-01-01	0.537020027637482
1979-01-01	0.548609972000122
1980-01-01	0.583060026168823
1981-01-01	0.573469996452332
1982-01-01	0.568960011005402
1983-01-01	0.533770024776459
1984-01-01	0.563920021057129
1985-01-01	0.562539994716644
1986-01-01	0.633099973201752
1987-01-01	0.613370001316071
1988-01-01	0.609000027179718
1989-01-01	0.612049996852875
1990-01-01	0.625949978828430
1991-01-01	0.643429994583130
1992-01-01	0.659150004386902
2001-01-01	0.683189988136292
2002-01-01	0.669189989566803
2003-01-01	0.686479985713959
2004-01-01	0.663200020790100
2005-01-01	0.688069999217987
2006-01-01	0.687049984931946
2007-01-01	0.696590006351471
2008-01-01	0.705039978027344
2009-01-01	0.709060013294220
2010-01-01	0.711250007152557
2011-01-01	0.725310027599335
2012-01-01	0.743200004100800
2016-01-01	0.763050019741058