Year	% of total
1990	57.7434836105205
1995	61.172393102029
2000	51.7107756011985
2005	49.3245003183177
2010	50.1483523313364
2011	61.734255633719
2012	43.6761396431203
2013	40.8734463492338
2014	31.2493357509293
2015	28.8925661082475
2016	20.7018963548796
2017	20.601606678315