Year	% net
1970	65.29409
1971	64.46607
1972	65.3877
1973	66.66492
1974	68.47037
1975	70.56163
1976	71.99129
1977	72.78758
1978	72.20472
1979	72.21722
1980	73.09312
1981	74.37184
1982	75.82499
1983	76.1335
1984	76.81317
1985	77.73915
1986	77.29259
1987	77.11973
1988	76.75809
1989	76.01112
1990	74.63802
1991	74.73087
1992	74.09309
1993	74.0436
1994	75.16011
1995	75.02232
1996	75.48158
1997	75.5107
1998	75.60902
1999	75.71902
2000	78.51549
2001	79.62317
2002	80.44252
2003	80.96071
2007	82.43302
2009	82.80717
2010	83.62232
2013	84.09792
2014	84.30141
2015	84.65189
2016	84.85931
2017	85.42188
2018	85.41373