Year	% net
1981	95.59286
1982	96.40157
1983	98.15753
1984	98.92843
1985	99.02563
1986	98.62751
1987	98.9879
1988	99.15072
1989	97.94835
1990	97.84123
1991	98.31617
1992	97.33748
1993	96.83258
1994	98.57861
1995	98.44747
1996	98.0899
2004	98.1757
2005	96.20132
2006	96.63566
2007	97.2263
2008	97.034
2009	97.04203
2010	96.85161
2011	97.96883
2012	98.35611
2013	98.60111
2014	98.28347
2015	98.50205