Just the four in North America. I had a mad moment of inspiration, along the lines of, "This is the one shot I'm going to get to apply to a globally ranked school, and if I'm going to do that, I might as well shoot for the very best, because I'm not leaving the UK for anything less". It's likely that I can get an unfunded PhD position at my current university in the UK if I don't get accepted anywhere else, so I looked at the applications as very labour-intensive lottery tickets more than anything else