Year	% net
1972	91.13997
1973	89.97293
1974	92.19333
1975	91.25173
1976	90.88845
1977	90.30083
1978	89.93416
1981	78.88961
1982	84.37641
1983	83.11006
1984	81.7267
1986	81.77756
1987	78.59312
1988	84.90042
1999	96.15628
2000	95.83488
2001	95.97568
2002	96.10443
2003	94.91876
2004	95.62663
2005	96.25162
2006	96.52911
2007	96.62426
2008	95.79417
2010	92.73811
2011	92.06646
2012	92.96656
2013	92.73666
2014	93.34251
2015	94.91362
2016	95.5354
2017	95.03083