Year	% net
1971	32.22932
1972	34.52219
1978	53.79596
1979	55.89836
1980	56.81116
1982	54.98564
1983	54.71833
1984	47.77643
1985	46.34194
1986	42.86991
1987	49.56997
1988	50.44962
1989	50.78367
1990	52.61447
1991	55.42146
1994	52.62158
1995	60.95711
1996	67.47189
1997	66.01122
2001	79.09826
2003	80.56632
2005	82.69166
2007	82.74813
2008	83.95373
2014	87.1824
2015	88.89822
2016	86.86441
2017	88.03994
2018	88.30915