Year	% of total
1990	58.5107308682132
1995	47.9997443950618
2000	40.0006103421932
2005	40.4298381164053
2010	44.7786564580017
2011	47.1724146870299
2012	38.0512713821206
2013	38.5827747226683
2014	25.0714053770514
2015	29.0213335236849
2016	23.4919336665191
2017	24.3721542771003