Year	% of total
1990	98.3226396181497
1995	98.3364442477786
2000	98.3970997949461
2005	98.4244083605388
2010	98.5119802847897
2011	98.4839814202241
2012	98.5190338715528
2013	98.5251680883384
2014	98.4969423230495
2015	98.4948299766255
2016	98.5198485373132
2017	98.5338345416421