Year	%
1971	72.68005
1972	72.09414
1973	73.05481
1974	75.28548
1975	79.3036
1976	75.82981
1977	78.47501
1978	70.85332
1979	77.7382
1980	79.00768
1981	79.92212
1982	82.21141
1983	83.23208
1984	82.48792
1985	85.094
1986	84.85634
1987	84.93914
1988	85.49878
1989	87.2372
1990	85.83101
1991	88.52283
1992	88.48546
1993	88.77381
1994	88.8839
1995	88.79104
1996	89.16258
1997	89.18019
1998	89.2055
1999	90.3527
2000	90.21805
2001	91.44694
2002	91.8274
2003	91.83506
2004	91.41852
2005	90.62327
2006	90.68009
2007	90.66842
2008	90.5528
2009	90.52804
2010	90.14646
2011	89.71483
2012	86.4415
2013	86.94968
2014	87.71369
2015	88.19032
2016	89.50132
2017	90.15284