Year	% net
1971	77.81724
1975	75.72307
1978	77.84231
1979	79.28226
1980	81.34724
1981	83.07554
1982	85.66261
1983	88.7141
1984	91.55791
1985	92.39317
1986	93.27848
1987	93.81994
1988	94.15208
1989	94.54256
1990	93.78617
1991	94.78237
1992	95.16143
1993	95.99043
1994	95.99787
1995	96.22811
1996	95.26425
1997	94.13777
1999	93.52937
2000	95.23478
2001	97.08488
2002	98.33273
2003	97.86293
2004	97.63585
2005	98.74059
2006	97.29862
2007	96.12795
2008	96.3229
2009	97.53303
2010	98.15464
2011	98.82468
2012	97.47715
2013	97.80391