Year	Ratio
1980-01-01	0.346769988536835
1981-01-01	0.371170014142990
1982-01-01	0.313230007886887
1983-01-01	0.311489999294281
1984-01-01	0.284209996461868
1985-01-01	0.288580000400543
1986-01-01	0.298940002918243
1987-01-01	0.334639996290207
1988-01-01	0.321770012378693
1989-01-01	0.246940001845360
1990-01-01	0.354820013046265
1991-01-01	0.352820008993149
1992-01-01	0.361000001430511
1993-01-01	0.316190004348755
1994-01-01	0.368079990148544
1995-01-01	0.416629999876022
1996-01-01	0.429479986429214
1999-01-01	0.378289997577667
2000-01-01	0.378670006990433
2002-01-01	0.410420000553131
2004-01-01	0.544059991836548
2005-01-01	0.543560028076172
2006-01-01	0.503030002117157
2007-01-01	0.502789974212646
2010-01-01	0.607150018215179
2011-01-01	0.638180017471313