Samik is right - this is considered Confidential and Proprietary information by the airlines. To the extent that they are now actively lying to customers and aggregators.
I was recently on a US Airways flight which showed 90% booked when we went to get seats. It turned out to be about 20% full.
Similarly because the airlines don't like what Kayak et al are doing, they are starting do set up "Just in The Moment" fares and seat availability. And they are tracking the source of the query and changing the data based on that.
Again personal experience - via Kayak, found a fare that was truly the lowest cost fare. Clicked on the link and got sent to the actual airline reservation flight only to find that the Flight Date and Ticket Price had changed between Kayak and the airline.
So while I wish you luck in your effort, I doubt its likelihood of success. The data you seek is company proprietary information. And it is not revealed outside the company (given the practice of overbooking) . chasing this one is just going to result in tears.