Year	% of total
1990	99.34545396488686
1995	99.33750669768611
2000	99.39267210974751
2005	99.45482610896738
2010	99.41246338950411
2011	99.51436553493126
2012	99.37226846929346
2013	99.02294217469411
2014	98.68016712417713
2015	98.65159401697171
2016	98.14700921055054
2017	98.059422858007