The average cost of marketing per loyal user of iOS apps in the U.S. increased to an all-time high in December 2011, according to marketing firm Fiksu.
Fiksu counts a "loyal user" of an app as those people who open the app three times or more.
The company's latest report suggests that the average cost per loyal user for App Store developers was $1.81 in December.
This figure is the highest recorded to date, up $0.38 compared to November 2011, which saw a cost per loyal user index of $1.43.
Fiksu said that "extreme marketing" around the Christmas period caused this increase, as advertisers spent heavily to drive their games up the store rankings before the top lists were locked for four days over the Christmas period.
The report also noted that dollars spent by users on iOS apps increased by 100 percent in the final week of December compared to prior weeks, giving advertisers the opportunity to acquire twice as many loyal users.
Fiksu's latest report also revealed that the daily average number of free iOS app downloads reached an all-time high in December,
beating November's previous record.
On average, 6.04 million downloads of free apps were recorded daily during December, topping November's 5.65 million daily downloads.
