Year	% of total
1990	99.61821974808
1995	99.644207349747
2000	99.5907738973168
2005	99.6562711595522
2010	99.7906437133979
2011	99.6029496839861
2012	99.5849409541285
2013	99.3779978448902
2014	98.8743152864247
2015	98.1361401237551
2016	97.558943417747
2017	97.1943596926821