That's amazing. I'm surprised Asia hasn't even reached twenty million downloads, though.
India's probably got the most downloads because of the large IT industry there. There's a large population but most don't have access to computers. Compare that to China, where many more people have access to computers, but the Firefox 4 download rate is much lower.
Indonesia's the exception - Firefox has a share of something like 80%. No idea how that happened.
Japan's pretty tech savvy as well and has a high rate of technology penetration.
http://blog.mozilla.com/gen/2010/06/29/mozilla-in-indonesia-...
Which is a good thing for Microsoft but a bad thing for Asia.