Year	% net
1971	23.6455
1972	25.7878
1999	43.44936
2000	46.69309
2001	50.29946
2002	52.82522
2003	54.57474
2004	57.02298
2005	58.8284
2006	62.24543
2007	64.54108
2008	66.01777
2009	67.97699
2010	68.17434
2011	69.26989
2012	71.64773
2013	71.91605
2014	72.0409
2015	72.00123
2016	70.70959
2017	69.83931