Year	% net
1971	65.27091
1972	66.60876
1973	71.99019
1974	75.2748
1975	77.93356
1976	79.58609
1977	80.45519
1978	81.26704
1982	85.27954
1991	80.0726
1992	81.63788
1995	84.93426
1996	84.65288
1997	83.61115
1998	90.30869
1999	92.3316
2000	93.21932
2001	93.56763
2002	94.84328
2003	95.37459
2004	96.12372
2005	96.33118
2006	96.36581
2007	96.96115
2008	96.39946
2009	97.6914
2010	98.01097
2012	98.72828