Year	% of total
1990	99.9617372631112
1995	99.5492792428496
2000	97.9660948944068
2005	97.1396754720324
2010	96.0990141660438
2011	98.9586816259961
2012	85.4742336319957
2013	78.750293564805
2014	82.8343073187766
2015	75.1874411831808
2016	57.0917623810824
2017	56.9144561104444