Year	% net
1971	63.88022
1975	61.17866
1978	64.98599
1979	67.30062
1980	69.60487
1981	72.21471
1982	75.74594
1983	79.479
1984	83.0866
1985	84.70119
1989	88.93155
1990	88.86232
1991	90.33445
1992	91.21126
1993	92.62225
1994	93.08855
1995	93.97818
1996	93.36097
1997	92.85678
1999	92.94753
2000	94.97846
2001	97.40203
2005	99.96022
2006	98.58952
2007	97.18791
2008	97.24187
2009	98.60494