Year	Ratio
1971-01-01	0.382600009441376
1972-01-01	0.356669992208481
1973-01-01	0.367749989032745
1974-01-01	0.358579993247986
1975-01-01	0.362210005521774
1976-01-01	0.376929998397827
1977-01-01	0.374680012464523
1978-01-01	0.363660007715225
1979-01-01	0.334520012140274
1980-01-01	0.344650000333786
1981-01-01	0.365889996290207
1988-01-01	0.380710005760193
1989-01-01	0.376610010862350
1990-01-01	0.360500007867813
1991-01-01	0.366329997777939
1992-01-01	0.393389999866486
1993-01-01	0.449369996786118
1996-01-01	0.519500017166138
1997-01-01	0.536970019340515
1998-01-01	0.554799973964691
1999-01-01	0.577189981937408
2000-01-01	0.589510023593903
2001-01-01	0.595570027828217
2002-01-01	0.589269995689392
2003-01-01	0.604690015316010
2004-01-01	0.599590003490448
2005-01-01	0.619870007038116
2006-01-01	0.619130015373230
2007-01-01	0.606440007686615
2008-01-01	0.597800016403198
2009-01-01	0.593519985675812
2010-01-01	0.663680016994476
2011-01-01	0.635349988937378
2012-01-01	0.660679996013641
2013-01-01	0.671519994735718
2014-01-01	0.697269976139069
2015-01-01	0.704379975795746
2016-01-01	0.725969970226288