Year	% of total
1990	99.9560400266882
1995	99.9548770433779
2000	99.9418264891325
2005	99.9323147582578
2010	99.9516056451077
2011	99.9524920033498
2012	99.9530300718569
2013	99.9532556414695
2014	99.9540650862187
2015	99.9547681162726
2016	99.9553471523347
2017	99.9558234947612