Year	% of total
1990	44.83567256080007
1995	41.55554118431234
2000	39.94860409828621
2005	41.81021212905025
2010	35.79403647879575
2011	43.92058457027917
2012	26.648220027333526
2013	19.435787412694967
2014	10.775505318390824
2015	7.706916864652417
2016	3.0166348523187696
2017	3.0224828265248833