I work with Android, but to answer anyway, I have never paid for an app. I do have 2 apps that normally cost $0-$2, but I managed to download them for free. It's like you said, for every paid app, there is usually a free substitute that works equally well, or even better. Those usually have ads, but as long as it aren't popup ads, I don't mind.
If those apps still count as paid, and default apps don't count, then I would say my ratio would be 85% Free and 15% Paid. But yeah, I don't think not having paid for them make it actually count, so I daresay, all of the apps I downloaded were free.