Year	% of total
1990	12.3408877483776
1995	13.8994524563906
2000	16.9741257460006
2005	15.5548206068401
2010	20.049019220481
2011	18.1639891020705
2012	18.85184427287
2013	16.8829799116276
2014	16.4392204221895
2015	12.8280950114367
2016	6.15841859356653
2017	6.23623457005759