Year	% net
1970	81.71546
1971	82.02622
1972	82.59541
1973	83.44274
1974	84.13042
1975	84.35726
1976	85.13972
1977	86.1414
1978	86.74287
1979	88.45204
1980	88.9761
1981	90.17954
1982	90.46124
1983	90.60572
1984	90.50709
1985	90.97202
1986	90.73254
1987	90.88164
1988	90.58643
1989	89.74002
1990	90.26429
1991	90.62783
1992	91.3644
1993	91.65882
1994	91.12024
1995	90.98518
1996	91.39955
1997	91.36983
1999	93.3449
2000	94.03296
2002	93.97929
2003	93.11855
2004	93.49142
2005	94.49856
2006	94.26617
2007	93.96783
2008	94.93857
2009	95.03911
2010	94.9917
2011	94.81959
2012	95.06219
2013	93.80947
2014	93.71312
2015	93.68508
2016	94.03409
2017	93.9758
2018	93.96438