Year	% of total
1990	99.9380991377785
1995	99.9363268645168
2000	99.9443700971652
2005	99.9408004364417
2010	99.9370387677268
2011	99.9362739963048
2012	99.9355017137252
2013	99.9347175838211
2014	99.9339198801701
2015	99.5312152983186
2016	97.0749574788319
2017	95.9998593070447