Year	% of total
1990	98.94583264788503
1995	98.76618325932608
2000	98.75477889573446
2005	98.77892563070588
2010	98.79088115853094
2011	98.78222425208591
2012	98.60853582815382
2013	98.53582674590442
2014	98.36080182858332
2015	98.42037198719797
2016	97.96652397998639
2017	97.94979992646404