The iPad ushered in the new age of tablet computing in the spring of 2010. In the two-and-a-half years since, the market for tablets has exploded, as if people were just waiting for such a device to offered. There are currently no signs that this trend is going to slow.

In fact, the Pew Research Center’s Project for Excellence in Journalism today released new statistics showing that 22% of U.S. adults own a tablet device, up from 11% in July 2011. Of course, back in 2011, Apple’s iPad was still almost the only game in town. Pew’s numbers show that the iPad represented 81% of the tablet market in 2011, with Android tablets making up only 15% of the rest.

This year, the full effects of Amazon’s Kindle Fire and the rise of the 7-inch tablet market can be seen. The iPad now only makes up 52% of the tablet market, while Android devices make up the other 48%. Kindle Fires (which run on a version of the Android operating system) make up 21% of the market alone. Pew states that 68% of tablet-owning adults purchased their tablet in the past year.

It’s clear that as enthusiastic as consumers were for the iPad, many were waiting on a lower-priced tablet. Apple will attempt to enter (and will likely dominate) the 7-inch tablet market later this year with the iPad Mini. It will face more competition than it ever has, though. Amazon recently announced its updated Kindle Fire lineup, and Google is rumored to be launching a $99 tablet before the end of the year.

Even in the 10-inch tablet market Apple will be facing new competition. With the release of Microsoft’s new hybrid tablet/desktop Windows 8 operating system, manufacturers such as Samsung and HP have announced tablet devices for every niche, including enterprise.