Year	%
1971	70.19079
1972	70.70371
1973	71.96136
1974	74.16329
1975	78.15375
1976	75.10897
1977	77.64336
1978	70.92904
1979	77.13656
1980	78.4185
1981	79.13295
1982	81.18886
1983	82.15027
1984	81.75074
1985	84.30308
1986	83.24096
1987	83.86425
1988	84.82985
1989	86.2486
1990	85.36801
1991	88.10619
1992	88.49523
1993	89.01336
1994	89.0503
1995	89.02055
1996	89.30571
1997	89.326
1998	89.34758
1999	90.32055
2000	90.16124
2001	91.32652
2002	92.8451
2003	93.13062
2004	90.7678
2005	89.50512
2006	90.99367
2007	91.30304
2008	91.4833
2009	90.87321
2010	90.54316
2011	89.88857
2012	86.08582
2013	86.8524
2014	87.69206
2015	89.10667
2016	90.97422
2017	91.53073