Year	Ratio
1971-01-01	0.981379985809326
1972-01-01	0.983359992504120
1973-01-01	0.979510009288788
1974-01-01	0.981270015239716
1989-01-01	1.000669956207280
1990-01-01	0.997240006923676
1991-01-01	1.006669998168950
1992-01-01	1.000929951667790
1993-01-01	0.997389972209930
1994-01-01	0.997470021247864
1995-01-01	0.997669994831085
1996-01-01	0.996290028095245
1997-01-01	0.995310008525848
1998-01-01	0.991840004920959
1999-01-01	0.989459991455078
2000-01-01	0.987689971923828
2001-01-01	0.983820021152496
2002-01-01	0.981850028038025
2003-01-01	0.981480002403259
2004-01-01	0.985369980335236
2005-01-01	0.986530005931854
2006-01-01	0.989189982414246
2007-01-01	0.991110026836395
2008-01-01	0.983910024166107
2009-01-01	0.985729992389679
2010-01-01	0.984329998493195
2011-01-01	0.982270002365112
2012-01-01	0.981100022792816
2015-01-01	0.984589993953705
2016-01-01	0.987309992313385