Year	% net
1971	69.63283
1972	70.16538
1973	70.88821
1974	76.37927
1975	76.45966
1976	76.85301
1977	76.3547
1978	75.56237
1979	74.91492
1981	75.48359
1982	76.19073
1983	77.59335
1984	77.6929
1986	78.90449
1987	79.09325
1990	77.36734
1991	79.81852
1992	82.45051
1993	92.01898
1994	93.94423
1995	94.76502
1996	93.65534
1997	92.40783
1998	93.04822
1999	94.14851
2000	94.00301
2001	94.26583
2002	94.71601
2003	93.94223
2004	93.52305
2005	93.7873
2006	90.6005
2007	89.70987
2008	91.53865
2009	93.6041
2010	95.56562
2011	92.55985
2012	90.75171
2013	93.57803
2014	96.84913
2015	97.82696
2017	97.03468