I doubt you are going to find any definitive numbers on this. If Adobe has them, they won't release them.
As far as personal experience, my agency keeps all legal documents in pdf format. We have the stats that show that pretty much everyone that comes after them at least downloads them and we don't get calls saying that people can't open them so I'd assume that most people are going to have one version of Adobe Reader or another installed.
But it's simply a guess and I could be wrong.
Thanks for the info.
It surprises me that Adobe wouldn't have this kind of information, based on the old stats that they would release about the flash player.
I have no idea how you'd go about estimating online users, but I can suspect that Adobe could work with the partnerships that they have to mine statistics from Microsoft, Google, etc.
I think you're missing the point about PDFs. Adobe Reader is no longer the only tool. All of the following come with a PDF reader out of the box
- Windows 8
- Mac OS
- Android (phones/tablets)
- iOS (iPad/iPhone)
- And for older versions of Windows
-- Chome browser
-- FireFox browser
For anyone with a halfway recent purchase it's a struggle to find somone who can't read PDFs!