Year	% of revenue
1990	2.4203069657615113
1991	2.4257425742574257
1992	3.787480273540242
1993	4.310344827586207
1994	4.028925619834711
1995	4.574520413182489
1996	6.165004533091569
1997	3.662420382165605
1998	4.115800488315313
1999	4.474982381959126
2000	0.838638045891932
2001	1.191775680338284
2002	0.8030984427764352
2003	0.8453069660358884
2004	0.7264155061771511
2005	0.8660138196128678
2006	0.6608862756244299
2007	0.5553658343584109
2008	0.41215385028841284
2009	0.49970247147581925
2010	0.582782190543773
2011	0.5643190069869133
2012	0.5398479259077421
2013	0.7973801493939192
2014	1.954199004628824
2015	1.6239050527586272
2016	2.4389454957140546
2017	2.9445925828984607