Year	% net
1970	22.3261
1971	22.4466
1972	24.22104
1973	25.905
1974	26.88199
1975	28.83319
1976	30.78708
1977	32.83186
1978	34.7434
1979	35.94514
1980	36.87936
1981	37.48043
1982	38.74966
1983	39.67568
1984	40.67642
1985	41.79869
1986	43.65962
1987	44.96323
1988	45.7202
1989	46.8762
1990	49.47763
1991	49.9504
1992	49.79359
1993	51.26631
1994	53.72983
1995	54.39648
1996	55.00383
1997	56.62397
1998	58.32453
1999	60.07506
2000	61.34339
2001	62.26609
2002	63.06525
2003	64.17527
2004	65.49245
2005	65.51785
2006	65.81262
2007	65.44071
2008	66.89581
2009	68.7705
2010	68.84673
2011	71.20198
2012	71.53439
2013	69.52544
2014	70.20788
2015	70.95123
2016	71.86762
2017	72.42314
2018	72.89887