Research firm IDC and mobile analytics firm App Annie have teamed up for a new report into how mobile app developers are making their money. In a word: freemium. The study found that of the top 1,000 apps on Apple’s App Store and Android’s Google Play store, 83% are freemium – free to download but making money from in-app purchases and/or ads – while 92% of the total revenues made by those 2,000 apps are from IAP or ads. This, despite the fact that 80% of developers said that less than 5% of their users had ever paid for a single in-app purchase. These stats are familiar reading in the mobile games world, but the music industry is also thinking hard about music can prosper in an apps world dominated by freemium models. More stats: 58% of developers surveyed said they don’t use any advertising in their apps, although in some countries – India especially – ads account for nearly 70% of in-app revenues.