Year	% of total
1990	97.7285496109658
1995	97.6029261404455
2000	98.3479423535015
2005	98.3777328800703
2010	98.8195125345379
2011	98.5025174269762
2012	98.2743350286379
2013	95.5154679941505
2014	89.6482716784947
2015	87.036314640814
2016	72.1519561859893
2017	72.0910148592327