Year	% net
1971	85.53299
1972	86.89114
1973	88.47069
1976	98.15505
1981	95.30617
1982	93.19261
1983	93.36505
1989	99.7782
1990	96.64845
1992	89.22107
2000	95.50225
2001	94.46057
2002	91.74473
2003	91.25868
2004	89.78907
2005	90.20329
2006	91.85561
2007	95.58731
2008	96.96312
2009	94.49267
2010	95.69098
2011	93.91218
2014	93.18643
2015	94.08345
2016	95.91661
2017	94.19739
2018	95.73025