I was recently quoted as saying "50% of all deployed software is open source". That's an awesome quote. It has legs. I've seen it in a couple of articles now. The only problem?
I didn't say it.
However, I did say something like it. I have said, many times and in a variety of ways, "According to our studies, anywhere between 42% and 50%, depending on how you count, of open source software is licensed under the GPL." I usually say this as part of my stuff on GPLv3, and why it is important to understand.
The quote I see though is : 50% of all deployed software is open source
Which is pretty awesome, if true. Properly enumerating open source adoption has at the best of times been quite difficult, so I don't think that this is a provable number at any rate, ever.