Year	% of total
1990	59.6256430299434
1995	59.275497929665
2000	60.1326586876195
2005	58.7915501179684
2010	62.049829579275
2011	63.2122904534004
2012	67.4273758446666
2013	64.7401960714033
2014	65.5296982082864
2015	60.4353058448626
2016	61.7961454758601
2017	61.9843104799484