Year	% of total
1990	12.7389588821304
1995	11.9694180549173
2000	11.4105462250574
2005	10.7274971699786
2010	10.1317005674548
2011	12.1742431798473
2012	8.14141931691635
2013	1.68679715820433
2014	1.36932817311088
2015	1.451273664354
2016	0.963140486469405
2017	0.963513879180911