This seems like something that could be very expensive. Did you have a use case in mind?
Files are chunked when added into IPFS, so how many times should we say a file has been downloaded if the first half of its chunks have been downloaded 1000 times and the second half of the chunks haven't been downloaded at all? For example, a video that people only stream the first half of before switching to something else.
It's possible that a chunk of one file is also a part of another file. Which file do we count the stats for that block against when someone requests that shared file chunk?
On its face it seems like a nice-to-have kind of thing (not sure what I'd do with it, though), but what I'm getting at is that it seems like we'd need to keep track of statistics for every single block on the node. One of my nodes has 1.6 million objects in it -- that's a lot of blocks to track persistent stats for.