Year	% of total
1990	99.9794952292974
1995	99.6080811192517
2000	99.3565090671867
2005	99.5149947949509
2010	99.5500346799215
2011	99.2602528939341
2012	97.9709600275977
2013	96.5867702247195
2014	96.6290782272796
2015	92.2730865530648
2016	89.4114981713697
2017	89.0140461977576