Year	% net
1970	16.37003
1971	16.47109
1972	16.63759
1973	17.58438
1974	18.04978
1975	19.13518
1976	20.39103
1977	21.97249
1978	23.49892
1979	24.79357
1980	25.94134
1981	26.65381
1982	28.12939
1983	29.37792
1984	30.74762
1985	32.22337
1986	33.97015
1987	35.2121
1988	35.97369
1989	36.85577
1990	39.30151
1991	39.69981
1992	39.15298
1993	40.01995
1994	41.94779
1995	42.2805
1996	42.63363
1997	44.15798
1998	45.5894
1999	47.21783
2000	48.55836
2001	49.90597
2002	50.77715
2003	52.62142
2004	54.25793
2005	54.5644
2006	54.68707
2007	54.62016
2008	55.70579
2009	57.77316
2010	58.4782
2011	60.43056
2012	60.93871
2013	59.21884
2014	59.29569
2015	59.82032
2016	60.31467
2017	60.83393
2018	61.33394