Year	% of total
1990	99.9958583992726
1995	99.5809576315039
2000	96.955016819582
2005	94.0694231771908
2010	95.3280520780739
2011	99.613679386024
2012	91.5715090874739
2013	87.2279923691767
2014	82.193072590173
2015	85.2229246432742
2016	77.9688667260668
2017	77.7761244649377