Thailand has the largest foreign filings - slightly more than Malaysia. It should be pointed out that the Vietnam and Indonesia figures are estimates, based on previous years. Vietnam one would expect to see at the bottom of foreign filings, but Indonesia, the 4th largest country in the world? That's a reflection of the fact that it has not been on business radar screens for very long (mistakenly - see below).
The domestic filing levels show the true market size and compare closely to GDP levels between these countries. Thailand with an active local economy is sizable. Malaysia too, but it is a smaller country with slightly lower GDP levels. The Philippines numbers are low as the figures are multi class, with Vietnam the smallest economy here, but perhaps punching above its weight in domestic filings. And Indonesia being by far the largest economy of these countries has by far the most domestic trademarks, over double its largest naighbours.
Now the interesting part. Add the two Indonesian ingredients - huge local brand focused commerce plus few foreign filings and what do you get...? A trademark squatting problem. So now we know why so many foreign brand owners end up in court trying to cancel local copies of their marks.