Year	% net
1972	30.37216
1973	31.37763
1974	32.23606
1975	34.17619
1976	36.1848
1977	37.82921
1978	39.21477
1979	40.42599
1980	42.21245
1981	43.49122
1982	42.77159
1983	43.48847
1984	43.26664
1985	43.09718
1986	43.30138
1987	42.61195
1988	42.74269
1989	41.64787
1990	40.53856
1991	42.13702
1992	41.45529
1993	41.44452
1994	42.57322
1995	44.41263
1996	44.2244
1997	47.41482
1998	47.91597
1999	48.25785
2000	50.25977
2001	52.81287
2002	56.38552
2009	73.56813
2017	78.4134
2018	78.14911