If the fraction of answered questions is at present 523/524 = 0.9981, why Italian.SE gives "99% answered"? I've noticed that other sites with similar fractions of answered questions state "100% answered."
I think that I have the answer to this question. The problem was that, for a time, whenever you visited the unanswered questions page, only one question was found there, essentially the same one that it's there now. Nevertheless, this question was also unanswered, but for some reason didn't appear in the unanswered questions page. Now that this question has one upvoted answer we get "100% answered" again.
Maybe the question should be why a question which has only one downvoted answer (total score of -1) doesn't appear in the "unanswered questions page".