Year	% net
1972	78.16315
1973	78.51883
1974	78.78632
1975	79.46034
1976	79.30351
1977	82.55524
1978	80.3445
1979	77.7245
1980	78.5737
1981	82.27869
1982	88.10684
1983	91.24489
1984	94.83329
1986	98.66192
1990	97.79685
1991	93.33278
1993	93.37677
1994	94.10458
1995	95.03595
1996	97.05766
1997	97.95839
2004	95.10045
2005	96.5796
2009	97.32628
2012	94.64999
2013	97.22058