Year	% of total
1990	80.91925616954313
1995	79.33150657378076
2000	78.53917372517736
2005	78.60650131712141
2010	76.73724494072691
2011	79.39788035172337
2012	72.86719201204276
2013	70.09502063749102
2014	65.64379880762584
2015	65.00602833189495
2016	60.06879264467521
2017	60.12844412619997