Year	% net
1972	88.92227
1973	89.33904
1974	89.1625
1975	89.36731
1976	89.90976
1977	90.32189
1978	90.54474
1979	90.6924
1980	92.79688
1981	92.73261
1982	93.15941
1983	92.63535
1984	92.07125
1985	92.06759
1986	92.75313
1987	93.72327
1988	94.22672
1989	94.57422
1990	94.39818
1991	94.31439
1992	93.8225
1993	93.78694
1994	93.67421
1995	94.031
1996	94.12244
1997	93.68543
1998	94.90122
1999	94.72622
2000	94.79554
2001	95.02662
2002	94.61046
2003	94.93556
2004	94.73213
2005	95.08741
2006	95.50985
2007	95.8344
2008	96.14903
2009	95.93594
2010	95.58284
2011	95.58054
2012	95.57613
2013	95.57173
2014	95.80243
2015	96.26472
2016	96.41842
2017	96.22156
2018	96.14082