Year	% net
1972	88.6396
1973	89.1661
1974	89.00047
1975	89.2394
1976	89.83552
1977	90.27388
1978	90.50115
1979	90.62807
1980	92.90003
1981	92.85563
1982	93.34626
1983	92.75075
1984	92.30237
1985	92.32298
1986	93.05631
1987	93.95585
1988	94.48895
1989	94.88938
1990	94.81208
1991	94.78329
1992	94.38105
1993	94.27886
1994	94.11886
1995	94.46567
1996	94.45544
1997	93.98747
1998	95.05742
1999	94.88434
2000	94.95017
2001	94.9752
2002	94.60519
2003	94.91746
2004	94.66182
2005	94.98987
2006	95.35235
2007	95.76946
2008	96.07065
2009	95.68362
2010	95.49749
2011	95.30487
2012	95.57133
2013	95.45906
2014	95.65169
2015	96.04822
2016	96.43329
2017	96.15659
2018	96.15167