Half of all victims
It would be interesting to know the size of the ransoms paid. If an individual with one PC pays up to preserve the photos of their loved ones, personal accounts etc. with say US$100 that is one thing. If a corporation with 5k PCs and mainframe etc pays up US$100 per machine (or however it works) that is quite another. I would expect that the larger corporations would have better backup restore management, but for the ones that don't the ransom would be quite a lot.