Great link. Not surprising actually, considering the demographics of iOS users and that iOS includes iPod Touch and iPad.

Google usually talks Android numbers vs. iPhone. Apple usually talks about total iOS devices and often emphasizes the install base since they were out first and built a 100 million device install base before Android even launched. In this case, it's in Google's interest to talk about total iOS install base so that's what they did, even though they don't really compete with the iPod Touch directly.