Got it. I was coming at it from the angle of free games, but now that you mention it I understand for paid games number of downloads would be sensitive data!
How about number of page views, would making that public be possible? That stat is readily available and a good indication of the traffic for the game - in reality it only correlates to a fraction of downloads so you can only guesstimate from it. It would supplement nicely the number of reviews stat and isn't too sensitive hopefully?
But yes - a rank would be the icing on the cake!!! Basically what I'm aiming for is for my game Holey Suit to become the next Right Click to Necromance or RogueLight, it would be good to gauge how far I am from this ;)