Year	% net
1976	73.65674
1977	74.55711
1978	74.85666
1979	75.2133
1980	75.73163
1981	75.99146
1982	76.42554
1983	76.86349
1984	77.10334
1985	77.68977
1986	78.80975
1987	79.47338
1988	79.66166
1989	79.95126
1990	80.08004
1991	80.31531
1992	81.03798
1993	84.11825
1994	86.37727
1995	86.51526
1996	86.77515
1997	86.68348
1998	85.45202
1999	85.58653
2000	86.42274
2001	86.85208
2002	87.87833
2003	88.13964
2004	88.46374
2005	89.66548
2006	89.75011
2007	89.43174
2008	90.20431
2009	90.42342
2010	90.87865
2011	90.14548
2012	89.82515
2013	90.12724
2014	90.43429
2015	90.75532
2016	90.89809
2017	91.11692
2018	91.13372