Year	% net
1973	31.39043
1974	33.39762
1975	35.17961
1976	36.70275
1977	39.89277
1978	43.71674
1979	48.15607
1980	50.17009
1981	51.79583
1982	52.33762
1983	52.80572
1984	52.45001
1985	51.12145
1986	49.36654
1987	47.89073
1988	47.34493
1989	46.0266
1990	46.02595
1991	47.30611
1992	46.89934
1993	47.87854
1994	48.18995
1995	48.7739
1996	46.48168
1997	49.78087
1998	50.65651
1999	51.74051
2000	53.53211
2001	55.27406
2002	58.06895
2009	69.58555
2018	73.2737