Year	% net
1970	95.12735
1974	96.62253
1975	96.32775
1987	95.45755
1991	96.1759
1997	100
1998	99.31647
1999	99.16485
2000	98.92861
2001	99.0026
2002	98.95948
2003	98.87379
2004	98.57855
2005	98.81425
2006	98.85437
2007	99.13952
2008	99.13278
2009	99.09709
2010	98.7319
2011	98.91685
2012	99.05122
2013	99.11341
2014	99.44461
2015	99.49576
2016	99.10172
2017	99.184