Depends on how you define "real." The overwhelming majority are fairly easily identified. The bulk of those that are not in that group would probably be identifiable with more information. I'd say 5% or fewer are truly unidentified.Knowing what you do in your background Duke, do you think there are real UFO'S ?
The biggest problem is the unreliability of witnesses. The ability of most people to accurately estimate size/speed/distance of things they see is beyond poor, same with the ability to identify knowns like aircraft, satellites, balloons, etc. Throw in hoaxers especially all the things that can be done with PhotoShop and CGI, and things get even worse.