Year	% net
1981	88.80977
1982	86.89369
1983	83.41503
1984	91.23305
1985	93.88383
1986	95.42331
1987	97.23594
2001	97.414
2002	96.07467
2003	95.40711
2004	94.68033
2005	95.12574
2006	96.10751
2007	95.97881
2008	95.2566
2009	94.24483
2010	93.59526
2011	91.9733
2012	92.5222
2013	92.35761
2014	92.32356
2015	92.51481
2016	91.54659
2017	91.9506
2018	92.55145