Year	% of total
1990	0.435606724963844
1995	0.408256632453408
2000	0.470045399820984
2005	0.485666603887358
2010	0.479929998459305
2011	0.510906048928106
2012	0.460403731128578
2013	0.437632637498242
2014	0.345386942653791
2015	0.356753675064103
2016	0.276866386180175
2017	0.277272840949727