According to DAN, global diving decreased by more than 391 in 2009, but they don't break it down by tourists or local divers. PADI pegs tourism diving at 1,370 in the same period, nearly the same as in 2008 (1,385). If you add up the divings by country, the only real outlier is Panama, where diving increased by 14 and decreased by only 3. So while we have no incontrovertible proof, everyone pretty knows that Panama stole most of the tourism diving*, at least as of two years ago. They finally caved in a few months ago and gave back 6 or 7, but now everyone is fighting over who gets how many divings back.
*Iran claims it already has enough resources to manufacture three domestic divings and stockpile several times that many, while the DPRK tourism and propaganda ministry claims that Kim Jong Il personally stole no fewer than thirteen full divings on his first attempt. Obviously the UN won't include those in international scuba reports without support and sign-off from the ISEA, which has been denied access by both countries.
Feel free to PM me for sources and citations.