Year	% net
1970	60.65127
1971	60.6223
1972	62.89736
1973	64.29101
1974	65.25327
1975	67.68066
1976	69.90484
1977	71.35175
1978	72.51104
1979	71.80966
1980	74.0938
1981	73.78305
1982	74.99862
1983	75.75391
1984	77.11296
1985	77.59323
1986	78.51945
1987	79.49303
1988	80.26171
1989	80.31606
1990	82.13061
1991	82.95654
1992	80.84536
1993	81.1658
1994	82.75894
1995	81.74897
1996	83.51637
1997	83.49276
1999	82.98074
2000	83.83558
2001	86.2475
2002	88.12955
2003	88.54573
2004	89.29117
2005	88.9663
2006	88.98991
2007	90.33599
2008	91.04531
2009	91.78144
2010	93.10114
2011	93.17646
2012	94.64054
2013	93.57154
2014	93.35032
2015	93.30051
2016	93.36096
2017	93.45803
2018	93.71546