Year	% net
1972	93.86251
1973	95.14198
1974	95.97773
1979	98.66038
1980	97.77162
1981	95.07437
1982	93.56775
1983	93.37664
1984	91.76272
1985	90.04994
1986	90.46027
1987	92.09755
1988	92.01383
1989	92.23341
1990	91.9294
1991	91.62777
1992	93.92801
1993	94.79615
1994	97.06529
1995	96.89418
1996	98.80478
1997	98.59347
1998	96.92918
1999	97.8031
2000	97.92115
2001	98.02557
2002	98.35008
2003	97.33076
2004	97.43389
2005	96.63556
2006	95.8703
2007	96.46826
2008	96.27754
2009	97.87644
2010	98.55296
2011	98.54931
2012	97.81573
2013	97.78205
2014	94.98571
2015	93.98312
2016	94.46077
2017	95.57823
2018	97.73994