Year	% of total
1990	98.5921967520577
1995	98.8606865443064
2000	98.8094903044055
2005	98.8896347975443
2010	98.9617480991338
2011	99.0260747355417
2012	97.613715457459
2013	97.2508349327043
2014	92.9337613537489
2015	93.0097270083713
2016	90.4259273615005
2017	90.5215379777885