It depends on so many factors that there is no meaningful answer. Most of the sales on whole AJ fall mostly on Corporate and Cinematic genres but then again they have also most of the tunes. This leads into situation where some Corporate tunes will stay at 0 sales throughout all eternity and some tunes gain hundreds of sales each month.
In my opinion it all comes down to what your tunes search visibility initially is, how much that turns into early sales which then lead to better search visibility on the long run and better sales on the long run.
If you miss the initial visibility, nobody finds your tune and it is “lost”.
Getting initial visibility in the most competed genres is really hard, in less competitive genres it’s more easy but then you won’t get that many sales.