Year	% of total
1990	47.9977370375362
1995	44.694453712147
2000	43.0813450802919
2005	44.220561764174
2010	38.2130323583238
2011	46.6861985255353
2012	28.6580810105166
2013	20.8405573376878
2014	11.7312972136243
2015	8.46530650743068
2016	3.33443559203764
2017	3.34317037021352