Year	% of total
1992	100
1993	100
1994	100
1995	100
1996	100
1997	99.53271028037383
1998	99.48717948717949
1999	99.53271028037383
2000	99.52380952380952
2001	99.57081545064378
2002	99.61389961389962
2003	99.63898916967509
2004	99.64664310954063
2005	99.65277777777779
2006	99.25650557620817
2007	99.30555555555556
2008	99.30313588850174
2009	99.32203389830508
2010	99.35691318327974
2011	99.40652818991099
2012	99.44289693593315
2013	99.45945945945947
2014	99.48453608247422
2015	99.50738916256158