Year	% net
1977	81.09825
1979	81.6186
1980	80.53305
1981	81.20826
1982	82.36259
1983	84.38122
1984	83.79767
1985	83.00498
1986	82.6006
1987	82.84559
1988	83.61409
1989	84.18599
1990	84.90877
1991	86.72767
1992	87.70922
1994	93.92109
1995	90.4316
1996	93.93946
1997	92.2457
2013	95.63183
2014	95.75358
2015	96.27579
2016	96.97938
2017	97.71525