Year	% of total
1990	80.5230749069073
1995	76.5739216461343
2000	75.3123790000404
2005	74.7124250972626
2010	71.5049791292514
2011	77.1669206341866
2012	67.7810244798715
2013	63.9088251115587
2014	62.5557307690522
2015	62.7061294520705
2016	52.8664743048917
2017	53.2934816714168