Year	% of total
1990	99.9614978578775
1995	99.9596606716234
2000	99.9395276304749
2005	99.9401651559611
2010	99.9356518506868
2011	99.946543925136
2012	99.9334865198363
2013	99.9148656569667
2014	99.7621770966074
2015	99.7152655416406
2016	99.6566439991376
2017	99.6561265475774