Year	% net
1971	79.73376
1972	78.37997
1973	78.27648
1974	77.64639
1975	71.21885
1976	68.99792
1977	68.07847
1978	68.85246
1979	69.57221
1980	68.73242
1981	71.21244
1982	67.93621
1983	68.09789
1984	68.37382
1985	69.16519
1986	73.80319
1987	77.85594
1988	79.33486
1989	79.45967
1990	78.82103
1991	79.15245
1992	77.36127
1993	97.62945
1994	96.91663
1995	96.213
1996	96.11728
1997	96.28477
1999	95.3991
2000	95.31862
2001	94.96985
2002	95.94279
2003	96.14328
2004	96.11749
2005	99.34591
2006	99.21867
2007	99.04305
2008	98.70243
2009	98.74389
2010	98.96982
2011	98.719
2012	97.9124
2013	97.29695
2014	96.91133
2015	97.36852
2016	96.72966
2017	97.49342