Year	% of total
1990	48.856105839777
1995	49.8007296098643
2000	77.5001502706683
2005	77.0275990450736
2010	75.8744164182614
2011	78.3458763074447
2012	70.9675085897864
2013	62.6617976369691
2014	38.3624133981118
2015	38.3818368731621
2016	23.703228355512
2017	23.7072483836313