Year	% net
1975	95.1505
1976	92.50368
1977	92.97177
1979	96.48257
1980	96.50106
1981	96.40776
1983	97.44464
1984	96.24322
1985	95.49819
1986	95.70327
1987	97.76091
1988	94.64053
1989	98.10415
1990	97.36788
1991	95.72525
1993	92.6702
1999	90.09004
2000	91.57529
2001	91.40376
2002	91.06873
2003	89.77681
2004	91.53535
2015	84.96535
2016	84.05713
2017	82.51691
2018	81.0188