Year	% net
1971	44.26315
1972	44.19388
1973	44.37488
1974	44.90214
1975	55.42114
1976	56.31357
1977	57.35547
1978	58.51042
1982	67.68719
1983	68.13755
1984	68.39266
1986	67.4901
1987	66.99335
1988	60.9687
1995	65.99029
1996	69.39835
1997	69.35206
1999	83.9704
2000	83.93834
2001	80.66896
2002	79.99208
2003	80.10576
2004	79.72127
2005	82.97076
2006	83.49789
2007	84.14165
2008	84.99195
2010	86.77192
2011	86.47169
2012	85.92268
2013	85.70984
2014	84.97239
2015	84.43463
2016	84.63978
2017	83.58238