Year	% of total
1990	97.3987979893001
1995	97.6325171458391
2000	98.0609816447356
2005	97.7875647679091
2010	97.3193639479183
2011	97.9822977406295
2012	97.5014164083268
2013	95.7008925511473
2014	85.9628982235803
2015	80.748887974085
2016	76.1184394930762
2017	75.6984659326454