Year	% of total
1990	77.5763867053122
1995	76.3521627114267
2000	75.0308004263397
2005	74.1582474024899
2010	72.1511076627807
2011	78.7273850045324
2012	68.4927048970665
2013	60.6831517972401
2014	47.7191476810775
2015	55.1527248746452
2016	40.7243850026145
2017	41.115549425172