Year	% net
1973	13.31087
1974	18.88167
1975	26.28963
1976	27.2474
1978	34.77876
1979	37.80752
1981	42.8799
1982	45.48745
1983	48.5464
1984	54.95535
1985	57.36973
1986	63.22959
1987	65.4702
1988	64.82394
1989	65.9663
1990	67.16301
1991	68.2343
1992	69.59741
1993	72.95787
1994	74.20158
1995	75.65553
1996	78.29453
1997	79.0198
1998	79.55151
1999	81.18873
2000	82.12433
2001	83.19777
2002	83.29087
2003	81.82427
2009	92.97839
2011	95.44183
2012	96.42745
2013	94.2199
2014	93.88526
2015	94.06176
2016	95.01142
2017	93.28335
2018	86.25355