Since the launch of the iPad, its users have downloaded 3 billion apps cumulatively, reports ABI research. That’s 19% of all cumulative downloads from the App Store. This also means that the iPad has reached this benchmark half a year faster than the iPhone did after Apple launched the App Store in 2008.

As a comparison, ABI says that Android tablets are estimated to only have accounted for around 440 million app downloads so far.

“Discounting all those apps that were originally developed for Android smartphones, Android still trails greatly behind the iPad in terms of its tablet app offerings,” says research associate Lim Shiyang.

Shiyang attributes that lower number to the fact that Android tablets often suffer from fragmentation, stuck on older versions of Android, while newer apps require components up the latest versions.

“Many Android tablets in the market are still using older versions of Android,” says Shiyang, “which disadvantages users from enjoying the better effects of apps produced from more advanced software development kits.”

Additionally, a large portion of the Android tablet market, such as it is, is taken up by low-end tablets that can’t compete in terms of user experience.

As is usual with this kind of report, there are predictions made by the company about the effects of the latest version of Android on tablet penetration for the OS. Ice Cream Sandwich is indicated as a primary factor why users might take to Android tablets in higher numbers, and therefore purchase more apps.

This prediction has been made in the past, however, especially at the release of Gingerbread for tablets. It has yet to come to fruition and Android tablets maintain a significantly smaller portion of the market than the iPad. Only time will tell if ICS, along with the introduction of devices like the Kindle Fire and Nook, which run forked versions of Android, will actuate the wave of increase this time around.

API predicts Android app downloads for smartphones to hit 58 Billion by 2016, and says that 27 billion are expected for Apple’s iPhone. As of Q3 2011, there were 120,000 apps published specifically for the iPad. ABI makes no estimates that compare the eventual downloads of Android and iPad apps.