I would say that the top 70% of students in the top ten programs all have Quant GREs of 790 or above.
GPAs are harder to quantify; I would say that 70% might be above 3.5, but this is all very relative. Many state school engineering programs shoot for a C+/B- average while many private school humanities/soft science programs shoot for a B+/A- average in their classes.
I think it's fair to say that in terms of GPAs, the average student does 1-1.5 standard deviations above average in the most competitive programs, and maybe about 2 standard deviations above average in the other programs. If you have a 3.3 GPA from Georgia Tech in Electrical Engineering and the average GPA is a 2.5 with a standard deviation of .3, you're probably a very competitive candidate assuming you've got the GRE scores to match the academic performance. If you have a 3.6 GPA in Electrical Engineering from Brown (less competitive in engineering) and the average GPA is 3.7, you're probably less competitive (assuming no relevant work experience.)
IMHO, it's in the same league as Illinois, but take a look at US News and World reports. If your program ranks in the top 5 or maybe 10, you're probably in one of the most competitive programs. Knowing Michigan, I'm willing to bet that's probably the case for you.
US News also ranked the undergrad programs when I first entered- at least the top five.
One other good measure of the competitiveness at the undergrad level is average ACT/SAT score if your school breaks down the numbers by undergrad major. If your program's average ACT score is a 32 or above, it's probably fair to say your program qualifies as competitive. If it's below 28-29, it probably doesn't.
I hate to say it, but the non-English, and in fact, non-North-American schools are at a bit of a disadvantage when it comes to getting into American schools. The equivalent of UIUC in India, for example, probably doesn't show up on most American schools' radar screens, but most admissions committees know all the details of the strong and weak programs at almost every flagship state school in the US. That said, I'm sure British students have an advantage on us when it comes time to apply at LSE and the Indian students have an advantage on us when it comes time to apply at IIM. Things are probably the same in China. There are strong schools in nearly every country, and the smarter investment banks get that and hire accordingly.