Year	% net
1972	92.57017
1973	92.22044
1974	92.12511
1975	92.09185
1976	92.32606
1977	92.33407
1978	92.45964
1979	92.70827
1980	92.65081
1981	92.05526
1982	92.17379
1983	92.06862
1984	92.98852
1985	92.93647
1986	93.52364
1987	93.92684
1988	94.46506
1989	94.28719
1990	94.42387
1991	94.75297
1992	94.35771
1993	93.99448
1994	93.72663
1995	93.45778
1996	93.85328
1997	93.77974
1998	94.48115
1999	94.36985
2000	94.01475
2001	94.46448
2002	94.81182
2003	95.52639
2004	95.06001
2005	94.62559
2006	94.75058
2007	94.84232
2008	95.11745
2009	94.90468
2010	95.26217
2011	95.48155
2012	95.48998
2013	95.87507
2014	95.65832
2015	95.85017
2016	95.88464
2017	94.94759
2018	94.86631