Take this for what it's worth, but according to the 2011 Outcomes report, the probability of matching with 2 interviews (ranking 2 programs) is approx. 65% for AMGs and 30-35% for IMGs. As expected, there is a large disparity between AMG vs IMGs. Assuming an 80% cutoff at which one may reasonably feel confident in matching, an AMG would only need to rank 5 programs (5 interviews) vs. 8 programs for U.S IMGs and 10 for non-U.S IMGs.
With that said, there are many other variables that are also considered and these types of metrics risk providing either false reassurance or needless discouragement (I'm also a victim😉). Remember, you only need one program to like you, so treat every interview as if it's your only one.