Year	% net
1970	60.88557
1971	60.87571
1972	63.31558
1973	64.80905
1974	65.8449
1975	68.45858
1976	70.88682
1977	72.43461
1978	73.67188
1979	72.9527
1980	75.43035
1981	75.07701
1982	76.36585
1983	77.1464
1984	78.55701
1985	79.01274
1986	79.93085
1987	80.93091
1988	81.71783
1989	81.72082
1990	83.75987
1991	84.69778
1992	82.24096
1993	82.43984
1994	84.07174
1995	82.73616
1996	84.5331
1997	84.35946
1999	83.50782
2000	84.3524
2001	87.00016
2002	89.00367
2003	89.37694
2004	90.12072
2005	89.56867
2006	89.40352
2007	90.6891
2008	91.22364
2009	91.82472
2010	92.81373
2011	92.88045
2012	94.27588
2013	93.2752
2014	92.79609
2015	92.68831
2016	92.75588
2017	93.05634
2018	93.3991