Uruguay did not have enough data to be listed, but the years I took the Cambridge and Oxford language tests (FCE, Proficiency, etc.), Uruguayans were in the top spots (the #1 overall got a scholarship to Oxford, and she was Uruguayan).
Of course, the demographics very much the same as Argentina's so it wouldn't be a big difference (we're not an Argentinian province by political accident and meddling by Britain - not that we mind :) ).
I believe it. I know quite a few developers from there and aside from being quite talented at what they do, their English is excellent. But having spent little more than a weekend in the country I didn't want to assume they were a representative sample. :)
Of course, the demographics very much the same as Argentina's so it wouldn't be a big difference (we're not an Argentinian province by political accident and meddling by Britain - not that we mind :) ).