FWIW, I'm not logged in on every device. For example generally I'm not logged in on my mobile because I don't like typing on it. On a work computer I'm not logged in either.
Very. In the numbers above, 76% of page views are from users not logged in.
I was surprised it wasn't even higher, since I remember it as having been 95% in some past analysis. This is more likely because I measured it differently than because something massively changed.
Though I don't know how widespread such usage is.