Year	% net
1970	99.97071
1971	99.78223
1972	99.90039
1973	99.49733
1974	99.44087
1975	99.55984
1976	99.66491
1977	99.57774
1978	99.44377
1979	99.42159
1980	99.47348
1981	99.32086
1982	99.21189
1983	98.83112
1984	99.50991
1985	99.57958
1986	99.76006
1987	99.86021
1988	99.89206
1989	99.83033
1990	99.52082
1991	98.98018
1992	97.55025
1994	97.15521
1995	98.51207
1996	98.97884
1997	99.75817
2013	97.69366
2014	97.41885
2015	97.66835
2016	98.46686
2017	99.11677