Year	%
1970	94.97737
1971	94.9674
1973	95.23287
1974	95.40014
1975	96.57257
1976	96.15505
1977	96.26162
1978	96.35493
1979	96.36644
1980	96.60755
1981	95.87681
1982	95.84577
1983	96.31848
1984	96.78201
1985	97.40329
1986	97.2109
1987	96.96536
1988	96.97129
1989	97.06316
1990	97.30982
1991	97.48264
1992	97.23117
1993	96.99352
1994	96.32612
1995	96.94871
1996	97.23069
1997	97.03299
1998	97.41821
1999	97.5242
2000	98.0215
2001	98.00475
2002	97.98845
2003	97.93396
2004	97.94117
2005	97.81429
2006	97.63673
2007	97.69982
2008	97.73205
2009	97.59704
2010	97.61103
2011	97.57137
2012	97.55626
2013	97.66285
2014	97.68716
2015	97.66778
2016	97.74559
2017	97.81541