Year	% of total
1990	98.36087776853108
1995	98.2904047016681
2000	98.55225827153625
2005	98.45509553696752
2010	98.59105076958964
2011	98.70116835298609
2012	98.0512601358934
2013	97.68651900932134
2014	96.70344088453874
2015	96.40989401628147
2016	95.24986852082378
2017	95.0252139249359