If in January 2012 the average cost of an installation in the States was $1.30, then in December 2013 it reached $4.36, Superdata said.

The average monthly income from a mobile user for the same period increased only by about 38%. This led to a situation where the average CPI is an order of magnitude higher than ARPU.

A source: http://www.superdataresearch.comSuperdata is researching the digital distribution of games and the market for free-to-play projects in the USA.
It also regularly collects data on user behavior.