They do but I've been completely unable to find a retail broker who lets you trade them. If anyone has a line on that please post it.
I did, actually got someone who know what they were talking about. They apologized that none of the brokers on their list still offered it, said they didn't know of any others, and didn't seem too concerned about the fact they had an instrument effectively no-one could trade. The apathy was a bit frustrating actually, not sure why they even bother to keep it given the dismal trading volume.