it's marginal because they are involved only in street level stuff most of drugs are imported or produced by european groups, mostly italian, albanian and turks, moroccans are the biggest not-european importers it leaves to nigerians only a tiny part of that market, never heard they run large shipments, they usually move drugs through ovules put in mules stomach... even in drugs that is their main activity their role is are marginal
anyway if you don't believe it just ask other europeans here