Year	% net
1975	44.14032
1976	45.01094
1977	47.0966
1978	49.31935
1979	52.18261
1980	54.36884
1981	56.36833
1982	57.74603
1983	58.16264
1984	57.6007
1985	56.46411
1986	54.88216
1987	53.85594
1988	53.11044
1989	53.68852
1990	53.03132
1991	53.9275
1992	53.66038
1993	54.08422
1994	54.39291
1995	55.14253
1996	53.90559
1997	56.56134
1998	57.30789
1999	57.97583
2000	60.15395
2001	61.81827
2002	63.32185
2003	65.75941
2004	67.51068
2005	69.6722
2006	71.40384
2007	74.01668
2008	75.02371
2009	75.26271