To summarize the comments and to close my own answer
tab=noanswers » 37417 hitstab=noanswers » 37417 hits
- Questions with absolutely no answers
questions?sort=unanswered » 71200 hitsquestions?sort=unanswered » 71200 hits
- Questions can have answers with a score of zero
answers:0 » 41247 hitsanswers:0 » 41247 hits
- Closed or merged questions without any answer are shown too
