Students often overestimate how much the average paper gets cited. I’ve seen students look at a paper with 40 citations say, “Eh, can we really trust it with only 40 citations?”
In truth, most papers that get cited even a few times are legitimate papers (vs. junk), and in all fields 40 citations indicates a paper that has has a lot of expert eyes on it. That’s the point of citations in source verification work. It’s not necessarily about the quality of the paper–you need expertise to assess that, and a paper with 100 citations is not necessarily better than one that has 10. What citations show you, for a quick and dirty process, is that experts have read a certain work or author and found their work worthy of discussion. More citations don’t mean more quality, but they do mean more expert eyes have probably looked at it and found it worth either agreeing or disagreeing with in public.
If you still want to know averages, here’s a list of citation averages from 2011, but note that citations follow a power law, and any average here is far above the median.