Asymco analyst Horace Dediu has used the download and sales figures provided by Apple to calculate some interesting numbers. Because iPhone and iPad users have downloaded nearly 25 billion apps and Apple has paid developers $4 billion, that means each app downloaded earns iOS developers an average of $0.16.
In addition, Apple has sold approximately 335 million iOS devices to date. On average, each device results in 75 app downloads. That means every iPad or iPhone sold nets developers about $12.