Year	% net
1970	52.06735
1971	54.531
1972	54.09324
1973	54.69262
1974	54.63455
1975	56.6575
1976	58.06063
1977	57.32422
1978	55.43254
1980	64.11736
1982	62.73692
1983	63.16497
1984	61.61274
1985	65.61814
1986	64.41338
1987	65.90944
1988	66.02713
1989	64.23941
1990	66.6239
1991	69.14372
1992	72.50935
1993	73.33611
1994	74.38078
1995	72.81064
1996	72.33616
1999	78.42459
2000	81.00897
2001	84.02504
2002	90.23787
2004	92.62374
2005	92.4662
2006	95.88051
2007	95.63359
2008	96.43234
2010	94.89265