Year	% of total
1990	42.4732727319946
1995	50.7147541074314
2000	60.8178921318459
2005	59.5004471558504
2010	58.8158101780713
2011	63.2866609695915
2012	52.2973948180538
2013	48.7392482829549
2014	38.3266496967494
2015	37.0863758470209
2016	31.6574207220814
2017	31.2373987853307