Nitrogen tires

My old Jeep had nitrogen in the tires from the previous owner. The tires seemed to hold air well but I can't say it had anything to do with nitrogen. Buuuuuuttttttttttt... Lets apply logic to the theory. If the claim is that nitrogen won't leak out of tires and ambient air is 78% then tires should only leak down 22%. If the tires do leak down 22% and you top them off with air you now have 83% nitrogen. Now the tires would only leak down 17%. As the leak down and refills occue you could almost have 100% nitrogen.
Edit
I just read the previous post i am guilty of not reading all replies before I post.