Grossing means total earning anually usually. The Top Grossing in iTune is based on daily, weekly, bi-weekly, quarter, or annually? Because if it goes by annually, how did Brother in Arm 2, a game that has just being released, rank #2 on Top Grossing?
I think it may have to do with how much cash it's made considering how long it's been out. A ratio, maybe? Cash-made-so-far/Time. The time it takes to update has to be at least daily.
