Year	% of total
1990	80.52546331791073
1995	79.2312972132504
2000	78.34582210315617
2005	78.70717311606923
2010	76.7712455886096
2011	79.52180316840139
2012	73.08745621116962
2013	70.52746836456906
2014	66.09620948507782
2015	65.59098767714184
2016	60.58993191007244
2017	60.680205655104125