I haven't seen any production per year breakdown, but from what I've seen on discussions of VIN numbers, most of the E-31 V12 US production appeared to be between '91 and '92, therefore a large percentage had the opportunity to be ordered as 6 speeds. Considering the "relative" frequency that 6 speeds come up for sale, I would tend to put some stock in the 10% value. It would be great to find out all of this data, but BMW will not divulge any details.