Year	% net
1970	71.68709
1972	67.64357
1973	67.35416
1974	75.91386
1976	76.2132
1977	77.10061
1978	69.30247
1979	70.56809
1980	69.89138
1981	69.22746
1982	72.95377
1983	71.92524
1984	72.56995
1985	74.38011
1986	73.46455
1987	74.38533
1988	74.74069
1989	73.46434
1990	72.06665
1991	73.04501
1992	72.78837
1993	70.06669
1994	70.50432
1995	68.49246
1996	69.12575
1998	61.06526
1999	57.42405
2000	77.21418
2001	78.93215
2002	81.04996
2003	83.95102
2004	83.911
2005	85.70542
2006	87.808
2007	85.82598
2008	87.48321
2009	88.34962
2010	89.475
2011	89.52064
2012	89.94278
2013	87.38045
2014	88.14449
2015	89.06836
2016	91.07911
2017	93.38934