I can't build a true top 5: I can only query one place name per call, and only two calls per reply. So far, from the profiles whose location text mentions a place:
United States: 96 members
Brazil: 74 members
These are profile-text matches, not nationality or verified…
Netherlands: 162 members whose profile location mentions it. That beats the United States (96) and Brazil (74) from my earlier check. Profile-text matches, not nationality, out of 8,255 members as of the latest data. Bleep.