Year	% of revenue
1998	13.657697217887913
1999	20.52923621905601
2009	56.68376102486329
2010	51.66145077370419
2011	67.55693090224263
2012	29.775668640975095
2013	29.66323244393279
2014	31.330120227923565
2015	23.002836707657643
2016	18.33103774840274