Year	% of total
1990	99.9664325345453
1995	99.9659114432415
2000	99.8941247010182
2005	99.8867199497822
2010	99.7782480691262
2011	99.8901913784626
2012	99.6862090913687
2013	99.3397740859243
2014	98.456179023089
2015	99.236326090646
2016	95.8139344602986
2017	96.3436551597196