The reason that lead me to ask about this is the following paragraph I found on this page (some guidance written by a STEM-field professor at CMU for applying to grad school), he says,
I'm not a U.S. citizen -- how does that affect my chances?
Unfortunately, if you are not a U.S. citizen and you don't hold a green card, your chances for admission are very significantly reduced. One simple reason is that we get an overwhelming number of applications from overseas. The extra work and time we spend on cultural acclimation and language skills for these students means that we can only accept a few of them, and of course this is a very few out of a huge application pool. If you already have a degree from a U.S. institution, that helps considerably with this issue. Also, it is more difficult to obtain funding for non-U.S. students, and so further increases the effort required to bring them here. Historically about half of our department's graduate students are non-U.S., although that proportion tends to be closer to one quarter in my research group.
The bold italics are mine. I personally find the "cultural acclimation" argument utter nonsense, and the "language skills" seems even more nonsensical, since almost all programs require quite good TOEFL/GRE test scores. So I suppose my question has two components really, and it concerns PhD programs specifically:
Did you experience difficulties funding a student in your department (STEM field) solely because he was a non-US citizen? If so, does this influence your decision of admitting non-US citizens?
Does your department has a specific quota of non-US citizens to be admitted?
Edit: In light of the new statistic I found, it seems absurd to say international students (i.e. non-US citizens) have a hard time getting accepted, especially in ECE. I think the professor's remark above doesn't reflect the bigger trend (he is with the ECE department at CMU), and his research group (where the proportion of international students is about 25%) is more of an exception to the "rule".