Students often overestimate how many times the average paper gets cited. Students will look at a paper with 40 citations and say, “can it really be trusted with only 40 citations?” Most papers that get cited even a few times are legitimate papers (vs. junk). In all fields, 40 citations indicate a paper that has had a lot of expert eyes on it. That is the point of citations in source verification work. It is 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 paper that has 10.
What citations show you, is that experts have read a certain work and found the work worthy of discussion. More citations do not 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 is a list of citation averages from 2011. Note that citations follow a power law, and any average here is far above the median.