Year	% of total
1985	85.4
1988	90
1993	87.4
1998	90.4
2003	92.4
2005	87.2
2006	89.6
2007	93.1
2008	95.5
2009	97.5
2010	98
2011	99
2012	99.5
2013	99.8
2014	98
2015	99.9
2016	99.9
2017	99.9
2018	99.9