Year	% of total
1990	7.55593921263103
1995	7.8976144961658
2000	7.32234523153514
2005	7.87599597991898
2010	8.05553676031747
2011	8.93850729857949
2012	7.43132337899614
2013	7.1541020270896
2014	4.73334737369556
2015	4.9439913225545
2016	3.54967028772942
2017	3.57668867952704