Most places don't publish those sorts of things (the only one I know of off the top of my head is Cleveland Clinic, which says their average Step 1 is around 248).
I had a similar question to this recently. I did a bit of research and reckon it's impossible to gain any consensus - even within programs, I don't think people know what the mean scores are. Both FREIDA and NRMP are fairly unreliable as both give the indication that, once you score over 220 or 230, you'll match somewhere, but there's no information available for the individual programs.