Year	% net
1972	88.27831
1973	88.78543
1974	88.67663
1975	89.03417
1976	89.77627
1977	90.32522
1978	90.67078
1979	90.90689
1980	93.35172
1981	93.2324
1982	93.79054
1983	93.20598
1984	92.81407
1985	92.84719
1986	93.70948
1987	94.69945
1988	95.41492
1989	95.91319
1990	95.87782
1991	96.15144
1992	95.74717
1993	95.57972
1994	95.45015
1995	95.80693
1996	95.66925
1997	95.70267
1998	96.00702
1999	95.80369
2000	95.86041
2001	95.99161
2002	95.64442
2003	95.82675
2004	95.38938
2005	95.69963
2006	95.92782
2007	96.2156
2008	96.41794
2009	95.93247
2010	95.45566
2011	95.31247
2012	95.49442
2013	95.49673
2014	95.53327
2015	95.93661
2016	96.40116
2017	96.18972
2018	96.22047