Year	% net
1971	51.37061
1972	52.37885
1978	70.40387
1979	71.61063
1980	71.90201
1982	69.25949
1983	66.86987
1984	59.87843
1985	58.02037
1986	53.56068
1987	62.64358
1988	63.0018
1989	63.21882
1990	64.38609
1991	66.91344
1994	63.24378
1995	72.19138
1996	79.91571
1997	77.78246
1999	85.14646
2000	85.65132
2001	88.05615
2002	88.32934
2003	88.48861
2004	89.11649
2005	89.39777
2006	90.3895
2007	88.35913
2008	88.98036
2014	90.31769
2015	91.97388
2016	89.86424
2017	90.91577
2018	90.73097