Year	% of total
1990	42.7491560816293
1995	44.3191212637126
2000	47.7056418943654
2005	44.0365639158998
2010	46.4631156249157
2011	46.6734592653929
2012	41.9016253492277
2013	34.5284312666477
2014	30.7011442965925
2015	28.3882258228231
2016	18.8320122324934
2017	19.0164942213565