Year	% of total
1990	88.9953305952514
1995	89.4913766815271
2000	90.7914047732454
2005	89.7840830783103
2010	90.9381232942568
2011	91.9283745885836
2012	86.829230250407
2013	85.3347137545434
2014	77.1164730889402
2015	74.9277515309761
2016	67.9525591753989
2017	68.1350300575805