Year	% of total
1990	99.076079836588
1995	98.1922967788657
2000	97.4678072054672
2005	96.9837930669516
2010	98.4049698996647
2011	97.9275884740539
2012	94.4660187361279
2013	91.7103550457966
2014	91.2198494622449
2015	90.337216747766
2016	87.2277995034966
2017	87.2157694525718