Year	% net
1974	45.21239
1975	49.89324
1976	51.76743
1977	53.43007
1978	54.69191
1979	55.82492
1980	58.15624
1981	56.25611
1982	56.10629
1983	56.8148
1984	56.72453
1985	58.1332
1986	57.95434
1987	59.026
1988	60.63469
1989	60.2169
1990	61.62495
1991	62.96178
1992	63.18703
1993	62.4261
1994	64.26976
1995	65.97832
1996	67.68866
1997	69.34477
1998	70.35013
1999	71.78861
2000	71.22217
2001	72.1497
2002	72.20039
2003	71.68995
2004	73.73811
2005	72.70539
2006	72.57661
2007	72.77233
2008	72.90826
2009	72.6651
2010	72.18505
2011	72.26186
2012	70.9092
2013	70.01486
2014	70.64797
2015	69.71525
2016	70.7488
2017	71.10909
2018	71.72989