Originally Posted by Stiggles:
“You cant possibly know that and neither can anyone else.”
Lots of different companies have pointed toward those figures - companies that have information about a wide range of app useage that monitors background info on devices. They can detect if a device is jailbroken. So given a decent sized sample of a few million devices it's easy for them to deduce it.
Of 40+ people I know with iPhones or iPads, there are 6 who have jailbroken, but I know a lot of geeks. Of the ordinary people I know who have iPhones, which is definitely the majority, none of them have jailbroken.
It's not just companies that work with iOS that have that info. Android Market collects stats on OS version usage, device language, country location etc.