Total app download volume on iOS dropped by 30 percent in March, down to the lowest levels the platform has since September 2011.

According to user acquisition company Fiksu, in March the top 200 free iPhone apps in the U.S. saw an average of 4.45 million daily downloads, down sharply from February’s figure of 6.35 million downloads a day.

Fiksu pins the drop on two factors: the novelty of iPhones wearing off for new users that received the devices over Christmas and Apple’s bot crackdown. Apple issued a warning to developers using download bots to artificially inflate their app’s chart position on Feb. 6. Although February’s download volume did dip slightly — down 6 percent from January’s all-time high of 6.79 million downloads a day — it appears the full effects of the crackdown are now being seen.

Although download numbers dropped dramatically, the cost to acquire a loyal user remained steady in March at $1.30. Fiksu defines a loyal user as one who opens an app at least three times. With March’s figures largely unchanged over February’s, app marketing costs are largely in line where they were last summer, when the cost to acquire a loyal user was $1.20.

User acquisition costs hit an eight-month low in January, when they fell to $1.14.