Year	% net
1971	55.31763
1972	60.81075
1973	63.88534
1974	63.57231
1975	64.35845
1976	66.56629
1977	71.74721
1978	77.34045
1979	75.54382
1980	77.24723
1981	78.84504
1982	80.24472
1983	83.54158
1984	84.92807
1985	84.7819
1986	84.34625
1987	79.66392
1988	78.52063
1992	46.58486
1994	67.70678
1996	85.53804
1997	84.24244
1999	85.45721
2000	86.1538
2001	88.79821
2002	93.91602
2005	94.93018
2016	92.12699
2017	87.05552
2018	86.86493