I would say that at least 2/3 of all of the engineering, physics, and computer science students were foreign, the vast majority were asian.
No longer...due to new visa restrictions and the dot-com crash, the number of chinese nationals as graduate students in technical fields seems to have fallen sharply. Almost all of the incoming graduate students the last couple years in my university in my field (highly anecdotal, I know) are US nationals, as opposed to say 5 years ago.