Year	% net
1971	61.4527
1972	64.17983
1973	67.56446
1974	68.77779
1975	70.01025
1976	71.41738
1977	76.11513
1978	85.02354
1979	83.31411
1980	81.73304
1981	82.62142
1982	83.57238
1983	86.09256
1984	87.42429
1985	88.99564
1986	88.7421
1987	83.47732
1988	81.90468
1992	46.99573
1994	67.96727
1996	89.25154
1997	88.84661
1998	88.52773
1999	88.2934
2000	85.39184
2001	84.93984
2002	88.94481
2003	87.44694
2004	88.25737
2005	92.70689
2007	91.54554
2008	92.41341
2010	92.3455
2011	92.74123
2012	92.59959
2013	92.07642
2014	92.17298
2015	92.12953
2016	90.61364
2017	85.87088
2018	82.63321