Year	% net
1970	95.24851
1971	95.26369
1972	95.34521
1973	95.29286
1974	95.80841
1975	96.00871
1976	96.26553
1977	96.28534
1978	96.61024
1979	96.80896
1980	96.86926
1981	96.73132
1982	96.42694
1983	95.80159
1984	95.63141
1985	95.67453
1986	96.42887
1987	96.73818
1988	96.87924
1989	96.9887
1990	96.79845
1991	96.63955
1992	96.17692
1993	96.30841
1994	96.19459
1995	96.70039
1996	97.51924
1997	97.60993
1999	97.78102
2000	97.60168
2001	97.587
2002	97.38783
2003	97.16182
2004	97.12704
2005	97.8101
2006	97.85197
2007	98.01473
2008	97.88209
2009	97.64435
2010	97.61237
2011	97.85523
2012	97.85339
2013	97.87697
2014	97.42686
2015	97.58042
2016	97.57071
2017	97.44854