Year	Percent
1971	0.90181
1972	0.90863
1973	0.91419
1974	0.91979
1975	0.92528
1976	0.94484
1977	0.94628
1978	0.96314
1979	0.98756
1980	0.99898
1981	1.00869
1982	1.02493
1983	1.03522
1984	1.03479
1985	1.03045
1986	1.03143
1987	1.02125
1988	1.015
1996	1.02461
2012	0.99042
2013	0.9778
2014	0.97426
2015	0.97378
2016	0.9725