They don't release all the figures because boxing has always been basically like a cash business. They want to brag about sales figures, but they don't want the tax man to know exactly how much they all got. They release U.S. figures, but they don't release UK sales. Or TV sales to other countries around the globe. Or fees charged by venues that order the PPV and sell tickets themselves. Lots of creative juggling. It made a lot of money.