Year	% net
1973	10.60855
1974	11.13558
1977	15.12498
1978	16.14387
1981	19.20413
1986	23.33992
1989	22.57018
1990	22.9095
1991	23.5063
1992	21.42369
1997	24.02891
1998	24.37682
1999	25.95656
2000	26.82781
2001	30.35208
2002	33.80062
2003	37.50722
2004	40.98293
2005	41.3199
2006	42.0534
2007	43.23786
2008	47.23268
2009	51.04844
2010	54.06424
2011	58.7165
2012	60.38408
2013	60.83162
2014	60.13331
2015	61.62795
2016	63.57047
2017	65.12458