More phones shipped and its open-source strategy appear to be behind the fact that Android captured 44 percent of all mobile app downloads in the second quarter, compared to the 31 percent that Apple’s iOS grabbed, reports the technology market intelligence firm ABI Research.

In the second quarter, growth in iPhone shipments fell to 9 percent from 15 percent in the first quarter, while Android’s shipment growth rose to 36 percent from 20 percent. According to ABI, Android’s total install base now outweighs that of iOS by a factor of 2.4 to 1–a ratio that it says will reach 3 to 1 by 2016.

Android’s open-source platform has expanded the Android device install base, resulting in the growth in the number of third party multi-platform and mobile operator app stores, ABI reports.

Even though Android has more total downloads, Apple still leads in the number of downloads per user. Android’s app downloads per user still lag behind Apple’s by 2-to-1. ABI attributed this to Apple’s monetization policies which attract good developers resulting in a better catalog of apps.

Because of a surge in smart phone demand, the research company predicts that the number of mobile app downloads across the world will reach 29 billion in 2011, up from only 9 billion last year.

Read more at CNET ^[1].