Year	Ratio
1973-01-01	0.0460099987685680
1974-01-01	0.0395000018179417
1975-01-01	0.1068399995565410
1976-01-01	0.1034599989652630
1977-01-01	0.1561799943447110
1978-01-01	0.1653600037097930
1979-01-01	0.1736599951982500
1980-01-01	0.1550499945878980
1981-01-01	0.1671700030565260
1982-01-01	0.1427199989557270
1983-01-01	0.1307500004768370
1984-01-01	0.1941899955272670
1985-01-01	0.1655499935150150
1987-01-01	0.1819999963045120
1989-01-01	0.1679600030183790
1990-01-01	0.1414899975061420
2003-01-01	0.3069800138473510
2004-01-01	0.3077000081539150
2005-01-01	0.3355700075626370
2006-01-01	0.2858900129795070
2007-01-01	0.3242099881172180
2008-01-01	0.3509100079536440
2009-01-01	0.3477399945259090
2010-01-01	0.3633700013160710
2011-01-01	0.3734900057315830
2012-01-01	0.3388699889183040