Year	% net
1975	44.14801
1976	45.01787
1977	47.10303
1978	49.32532
1979	52.1877
1980	54.37299
1981	56.37235
1982	57.74995
1983	58.16637
1984	57.60424
1985	56.46791
1986	54.88631
1987	53.8598
1988	53.1141
1989	53.69212
1990	53.03517
1991	53.93127
1992	53.66401
1993	54.08776
1994	54.39659
1995	55.14609
1996	53.90923
1997	56.56455
1998	57.31096
1999	57.97852
2000	60.15606
2001	61.82027
2002	63.32423
2003	65.76163
2004	67.51267
2005	69.67395
2006	71.40532
2007	74.01797
2008	75.02489
2009	75.26385