Stack Overflow considers a question "Unanswered" if the OP did not "Accept" any of the given answers. This means that many of the "Unanswered" questions do in fact have answers.

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".