Year	Ratio
1971-01-01	0.0507399998605251
1972-01-01	0.0736299976706505
1975-01-01	0.0918800011277199
1976-01-01	0.1107299998402600
1977-01-01	0.1428200006484990
1978-01-01	0.1549199968576430
1980-01-01	0.1677599996328350
1981-01-01	0.1758899986743930
1982-01-01	0.1543900072574620
1983-01-01	0.1551599949598310
1984-01-01	0.1774300038814540
1985-01-01	0.1815599948167800
1986-01-01	0.1857199966907500
1988-01-01	0.2213799953460690
1989-01-01	0.1792500019073490
1990-01-01	0.1973499953746800
1991-01-01	0.2159299999475480
1992-01-01	0.2300699949264530
1999-01-01	0.2679899930953980
2000-01-01	0.3142499923706050
2001-01-01	0.1365099996328350
2002-01-01	0.1892700046300890
2003-01-01	0.4016500115394590
2009-01-01	0.2106000036001210
2011-01-01	0.5843899846076970
2012-01-01	0.6278600096702580
2013-01-01	0.7506399750709530