Year	% of total
1990	96.5651273487321
1995	96.3619081353888
2000	97.4815210427198
2005	97.7964903488339
2010	98.1381408576542
2011	98.3571053128066
2012	98.0742270029423
2013	97.7080159705244
2014	96.8341705588606
2015	97.9517847849117
2016	96.8317523332843
2017	97.0139805896742