Year	% of total
1990	99.6066996888105
1995	99.5809649285064
2000	99.5499711446191
2005	99.4115039164003
2010	99.4476413232427
2011	99.5304130879093
2012	99.2176885641081
2013	99.0264640003624
2014	98.3140640099954
2015	98.0219286945161
2016	94.1394599235076
2017	93.8528246666324