Year	% net
1970	82.27112
1971	82.60889
1972	83.177
1973	84.04736
1974	84.72103
1975	84.91805
1976	85.69155
1977	86.69009
1978	87.30001
1979	89.03866
1980	89.52496
1981	90.6039
1982	90.83577
1983	90.9137
1984	90.8256
1985	91.25376
1986	91.02754
1987	91.10189
1988	90.75282
1989	89.876
1990	90.32017
1991	90.63014
1992	91.48941
1993	91.80722
1994	91.26191
1995	91.15608
1996	91.64851
1997	91.40894
1999	93.68048
2000	94.35054
2001	94.62992
2002	94.45974
2003	93.8278
2004	94.0079
2005	94.19796
2006	93.91793
2007	93.62552
2008	95.054
2009	94.90829
2010	94.92005
2011	94.82564
2012	94.91061
2013	93.70186
2014	93.5498
2015	93.48366
2016	93.7016
2017	93.74894
2018	93.80971