Year	% net
1971	50.38854
1972	55.07287
1973	56.29637
1974	56.7926
1975	57.56031
1976	60.10059
1977	62.00223
1978	64.02107
1979	65.31781
1980	71.42819
1982	75.34419
1984	76.30285
1985	77.77186
1986	78.99694
1987	81.0754
1988	80.78249
1989	81.48012
1990	80.79063
1991	81.25462
1992	81.4163
1994	79.84033
1995	80.90449
1996	81.12858
1997	80.76816
1998	80.39055
1999	79.8864
2000	79.81704
2001	81.9838
2002	84.87402
2003	84.42879
2004	86.17291
2005	89.97076
2006	90.06458
2007	87.76634
2010	95.21512
2013	93.39264
2014	91.30938
2015	92.49466
2016	92.48486
2017	93.34588