Year	%
1970	63.96928
1971	70.74123
1972	79.23121
1973	79.33957
1974	79.85158
1975	80.43198
1976	82.20837
1977	82.41112
1978	84.10061
1979	85.39872
1980	83.67389
1981	87.4483
1982	86.75624
1983	82.36908
1984	82.97794
1985	84.91452
1986	85.1642
1987	85.60482
1988	86.05611
1989	87.33932
1990	88.18857
1991	89.74339
1992	90.67916
1993	89.74826
1994	90.55851
1995	90.91665
1996	91.28658
1997	91.83754
1998	93.01483
1999	93.53196
2000	93.75601
2001	94.85292
2002	94.49527
2003	94.0383
2004	94.05214
2005	94.16532
2006	94.47411
2007	94.39391
2008	94.8494
2009	94.62635
2010	94.6471
2011	94.47452
2012	94.66631
2013	94.77297
2014	94.645
2015	94.69701
2016	94.77442
2017	94.93605