Year	% of total
1990	99.3502024069026
1995	99.3737590980865
2000	99.2449699760891
2005	99.272596170052
2010	99.2864982318215
2011	99.3197611890526
2012	99.2994810676024
2013	99.301999621247
2014	99.1504517547802
2015	98.5762989258251
2016	97.594418737426
2017	97.6630177077565