Year	% of total
1990	99.9159343271675
1995	99.8990850052443
2000	99.8632951554286
2005	99.8646385472404
2010	99.8664782176002
2011	99.8669032629253
2012	99.8673458323804
2013	99.8678074754887
2014	99.8682898975584
2015	99.8687949785031
2016	99.8693233525484
2017	99.8698700280207