I would think Latin Americans would make up the majority of the non-US members. In many LA countries, American is considered a "home town airline." In high school I worked at DFW, and on the DFW-GRU flights, codeshared with TAM, I would venture to guess that at least 75% of the Brazilians flying who had a FF# on their boarding pass had an AAdvantage number - not a TAM Fidelidade one. Among those in J (and at the time there was also F), it was extremely rare to see anyone with a TAM #.

You could also take a guess by looking at which countries have dedicated AAdvantage phone numbers. The UK and Spain both do, for example. The call centers may be physically located elsewhere (i.e. Spain calls go to Mexico) but I don't think AA would bother with a disparate phone number if it were not for a lot of AAdvantage members.