You say that the static files being served are
not of a big size. The smaller they are, the more you'll be worried about packets per second instead of overall bandwidth on the network.
As with bandwidth, AWS doesn't publish any concrete numbers, only "Low", "Moderate", "High", etc. I ran into some problems with PPS limitations, and it was even less published than bandwidth numbers, so I ran some tests.
Here's what I found for various instance sizes:
There was a lot more that I found, too, around guaranteed throughput and best effort PPS (packets per second). I put it into a blog on monitoring packets per second on EC2 where I show graphs and tables better than I can show in a comment.
To tie it back to Amazon's Network Performance Designation ("Low", "Moderate", "High"), you'd probably be shocked to know there's little correlation between actual bandwidth and actual PPS to those designations. They are worthless - only rely on test results, not published categories from AWS.