Year	% net
1970	75.0327
1971	74.94596
1972	75.74485
1973	78.39076
1974	79.40055
1975	80.62448
1976	81.18557
1977	80.80983
1978	79.02141
1979	79.08262
1980	79.93978
1981	80.92632
1982	81.43809
1983	81.96486
1984	82.73018
1985	84.10689
1986	85.67678
1987	86.38137
1988	87.24715
1989	88.52851
1990	88.33225
1991	88.59171
1992	88.35504
1993	88.4584
1994	88.38402
1995	87.62904
1996	87.48163
1997	86.96593
1998	87.74478
1999	88.92792
2000	89.31958
2001	89.48382
2002	89.4318
2003	90.80218
2004	91.58107
2005	91.93671
2006	92.27432
2007	93.37933
2008	93.56321
2009	93.5293
2010	93.69719
2011	93.42632
2012	93.84734
2013	93.81791
2014	93.94306
2015	94.21628
2016	94.32115
2017	94.27793
2018	94.32971