Year	% net
1978	80.44977
1981	84.61138
1982	82.92038
1983	82.91407
1984	83.95341
1985	87.79888
1989	81.8244
1990	78.87825
1999	94.89956
2000	91.89882
2001	86.51719
2002	87.64809
2003	89.49912
2004	93.05113
2005	92.19581
2006	91.74959
2007	92.11493
2008	88.21988
2009	84.39782
2010	85.18712
2011	88.83452
2014	99.28103
2015	98.12713
2016	95.9634
2017	95.94098
2018	93.63078