Year	Ratio
1971-01-01	2.36121010780334
1972-01-01	1.94062995910645
1974-01-01	2.71573996543884
1975-01-01	1.45016002655029
2001-01-01	1.62548995018005
2002-01-01	1.67516005039215
2003-01-01	1.57881999015808
2004-01-01	1.51359999179840
2005-01-01	1.57756996154785
2006-01-01	1.66568994522095
2007-01-01	1.63268005847931
2008-01-01	1.60842001438141
2009-01-01	1.66259002685547
2010-01-01	1.59598004817963
2011-01-01	1.65714001655579
2012-01-01	1.65302002429962
2013-01-01	1.64112997055054
2015-01-01	1.60641002655029
2016-01-01	1.61678004264832