Year	% net
1970	21.34574
1971	21.49599
1972	23.42692
1973	25.25942
1974	26.30911
1975	28.40239
1976	30.48158
1977	32.63458
1978	34.66565
1979	35.93375
1980	36.79775
1981	37.30956
1982	38.53365
1983	39.36609
1984	40.31688
1985	41.39054
1986	43.32153
1987	44.67674
1988	45.38949
1989	46.52006
1990	49.25892
1991	49.72669
1992	49.52989
1993	50.93157
1994	53.41838
1995	53.95086
1996	54.46799
1997	56.10449
1998	57.8116
1999	59.56191
2000	60.76744
2001	61.63395
2002	62.36273
2003	63.43127
2004	64.71712
2005	64.59102
2006	64.80938
2007	64.23128
2008	65.65144
2009	67.52974
2010	67.34881
2011	69.73419
2012	69.84611
2013	67.29459
2014	67.82328
2015	68.61788
2016	69.63247
2017	70.16223
2018	70.61009