Intraday Realtime Trade Analysis type:
NWBO Equity RITA BMA <go>
That will only show you today. Bloomberg does not support that information historically. I have asked them to add it and it will come out in future releases.
The historicals are all on my twitter feed @ TC_Trader and I will post today's after the close. It is currently 76% hitting the ask and 18% hitting the bid.