I have a paper submitted for publication that will deal with that. But very briefly, on a complex issue that you've identified quite correctly, on the one hand, with the reduced prices, there's no question that Saudi Arabia has said explicitly that one of their purposes of the supply-management regime they created in OPEC to reduce prices was in effect to curtail the revenues of ISIS.
As you say though, the problem is that the cost of production is so low that even at a low price, let's say $50-plus a barrel, it's still profitable for ISIS. But as we heard from my colleagues, it's much less so than in the past. The thing is, of course, that smuggled oil has a criminal premium, if you could call it that. The criminals involved in that oil trade also want a share of the profits, so that limits their incentive to engage in smuggling.
But it's still significant. Your point is very well taken.