Year	Ratio
1992-01-01	0.971019983291626
1993-01-01	0.959299981594086
1994-01-01	0.964429974555969
1995-01-01	0.965669989585876
1996-01-01	0.968940019607544
1997-01-01	0.973029971122742
1998-01-01	0.972710013389587
1999-01-01	0.976570010185242
2000-01-01	0.981410026550293
2001-01-01	0.982370018959045
2002-01-01	0.980929970741272
2003-01-01	0.977299988269806
2004-01-01	0.977439999580383
2005-01-01	0.976329982280731
2006-01-01	0.973190009593964
2007-01-01	0.976199984550476
2008-01-01	0.974120020866394
2009-01-01	0.949069976806641
2010-01-01	0.950380027294159
2011-01-01	0.949190020561218
2012-01-01	0.949819982051849
2013-01-01	0.955160021781921
2014-01-01	0.954859972000122
2015-01-01	0.953450024127960