What is the statistic on how many MBs of bandwidth the average site uses per month?
I already tried a search, but I couldn't find it.

That's a good question! As a general rule, most small web sites use less than 1 GB per month. But at the end of the day, it varies from host to host, depending on what type of customer they target.

I read a statistic somewhere stating that only about 4% of sites use over 2GB per month.