Year	Percent
1971	0.8855
1972	0.87244
1974	0.8906
1975	0.87355
1976	0.86284
1977	0.91717
1978	0.91776
1979	0.9314
1980	0.94187
1981	0.95185
1982	0.95314
1983	0.94096
1984	0.94778
1985	0.94949
1986	0.96297
1987	0.96502
1988	0.96586
1989	0.97062
1990	0.96786
1991	0.97539
1992	0.96632
1993	0.97388
1994	0.97546
1995	0.98055
1996	0.97921
1997	0.98117
1998	0.9885
1999	0.99756
2000	1.00574
2001	1.01296
2002	1.02071
2003	1.03102
2004	1.0269
2005	1.02558
2006	1.02743
2007	1.02795
2008	1.03025
2009	1.03268
2010	1.03196
2011	1.03111
2012	1.03206
2013	1.02963
2014	1.03171
2015	1.03824
2016	1.04403