in reply to Unanswered Perl questions on Stack Overflow
A more meaningful filter might be: Questions with 0 answers
This filter counts the number of questions with no answers. There are currently about 3000 questions with no answers (5% of the total 65,400 questions with the "perl" tag). This means that 95% of questions have answers. That seems pretty helpful to me.
Note that I also filtered out those which are closed as duplicates, since they have links to answers.
Also note that some of those 3000 may have answers posted as a "Comment" instead of an "Answer".