Year	% net
1972	91.80701
1973	90.96042
1974	92.56489
1975	91.6181
1976	91.29715
1977	91.4723
1978	90.96099
1981	79.01427
1982	85.05187
1983	83.21852
1984	82.16016
1986	82.38878
1987	79.43545
1988	86.13674
1999	97.13656
2000	96.74894
2001	96.25154
2002	96.2528
2003	95.19081
2004	95.92661
2005	96.7155
2006	96.99142
2007	97.01571
2008	96.4472
2010	93.74643
2011	93.12443
2012	93.1884
2013	93.35035
2014	93.47321
2015	95.07074