Year	% net
1977	47.80115
1978	47.54392
1979	48.41172
1980	49.2635
1981	48.13536
1982	49.88996
1983	51.46646
1984	48.49775
1991	64.31997
1992	60.20326
1993	62.81165
1994	63.43808
2005	88.50918
2006	88.87461
2007	86.90861
2008	86.84284
2009	88.51842
2010	89.66293
2011	90.93651
2012	92.53151
2013	89.74637
2014	86.20502
2015	83.30269
2016	82.20211
2017	82.56218
2018	81.32889