Year	% of total
1990	7.23544129241804
1995	5.37048657601554
2000	4.98598981294508
2005	3.99581018561098
2010	4.32618337118563
2011	5.8845442967924
2012	3.59530858494528
2013	3.47508180805878
2014	3.67645214477458
2015	3.55514624121341
2016	3.59570267696731
2017	3.63648738190616