Year	% net
1971	58.64983
1972	57.43236
1973	57.15677
1992	48.13996
1994	66.04871
1996	87.75623
1997	85.73091
1999	79.69913
2000	81.71716
2001	82.39324
2006	84.09389
2007	86.2552
2008	84.35485
2009	81.75614
2010	85.37423
2011	85.26215
2012	84.76653
2013	83.14222
2014	81.49637
2015	84.50138