Year	% net
1971	80.76854
1977	88.42588
1985	99.74285
1986	100
1987	100
1988	99.10194
1989	96.63541
1990	98.37444
1991	98.00907
1992	98.24972
1993	97.81289
1994	97.01748
1995	96.53171
1996	96.06523
1997	96.07538
1998	96.73013
1999	97.53816
2000	97.67057
2001	97.91024
2002	97.5509
2003	97.53576
2004	97.66046
2005	97.87734
2006	98.05008
2007	98.0127
2008	98.08626
2009	98.23304
2010	98.0771
2011	97.98488
2012	97.92299
2013	97.57591
2014	96.79833
2015	96.07343
2016	95.69118
2017	95.30064