Wish I could rub my crystal ball and come up with an answer, but I can't. It simply takes researching each of the airlines to find that information. A four-year degree is valued by ANY airline, even if it's not required. Keep in mind that airlines can change their degree requirements on a whim so it would behoove anyone to get the advanced education. Plus, as there have been many other threads on this topic, it may give you a fall-back in case something happens with your flying career. May I ask why you are inquiring about this statistic?