Canadian indie developer Owen Goss has done a study involving 252 iOS developers that says that the top 20 percent of iOS developers are earning approximately 97 percent of all the game revenue. The top one percent of earners on the App Store take in over a third of the revenue.
By contrast, the 80 percent of iOS devs are splitting a three percent of all App Store game revenue. 25 percent of iOS studios audited made more than $30,000 in lifetime revenue, while the bottom 20 percent have made less than $200; another 25 percent admitted to making between $1,000 and $10,000 overall.
Source: streamingcolour.com