Year	% net
1971	96.54105
1973	95.15404
1974	94.52301
1975	97.27922
1976	98.30379
1977	99.97696
1978	99.98407
1979	99.97685
1980	99.95414
1981	99.90612
1982	99.093
1983	98.11419
1984	96.30331
1985	96.34697
1986	97.0215
1987	97.57306
1988	98.24894
1989	98.36512
1990	97.97447
1991	97.38874
1992	97.15609
1993	96.73898
1994	96.43436
1995	94.99609
1996	95.40056
1997	94.98368
1998	94.75605
1999	94.43508
2000	94.398
2001	93.85651
2002	93.85948
2003	94.8527
2004	95.2255
2005	95.50656
2006	95.63832
2007	96.41764
2008	96.53968
2009	96.68084
2010	96.98847
2011	97.57037
2012	97.88079
2013	97.38938
2014	97.04009
2015	96.9821
2016	96.65012
2017	96.38096