Year	% net
1973	88.57117
1974	88.57643
1976	92.76964
1977	93.78195
1978	96.23891
1980	95.78357
1981	96.30122
1984	97.95416
1985	99.44769
1986	99.64446
1987	99.51097
1990	99.71056
1991	98.83127
1992	99.62446
1993	99.7306
1994	99.01193
1995	99.47725
1996	99.57584
2000	97.01995
2005	97.96037
2006	97.76736
2009	99.19486
2010	99.31374
2011	98.84927
2012	98.94994
2013	98.81486
2014	98.39988
2015	97.45382
2016	96.73726
2017	97.56411