Year	% net
1970	95.68617
1971	95.68864
1972	95.74352
1973	95.44732
1974	95.57091
1975	95.45712
1976	95.46943
1977	95.38032
1978	95.60802
1979	95.67564
1980	95.71462
1981	95.42447
1982	95.34997
1983	94.9907
1984	94.86441
1985	94.57944
1986	94.989
1987	95.42216
1988	95.43023
1989	95.24949
1990	94.91878
1991	94.65054
1992	94.02398
1993	94.60851
1994	94.87823
1995	95.40566
1996	96.05786
1997	96.73156
1999	96.99704
2000	96.92621
2001	97.18111
2002	96.89326
2003	96.78405
2004	96.41265
2005	96.77551
2006	96.80176
2007	96.77446
2008	96.90748
2009	96.8095
2010	96.89155
2011	97.12856
2012	97.26783
2013	97.41658
2014	97.11725
2015	97.16903
2016	97.01525
2017	96.89752