Since your answer is "13-25", you are generating as many or more ideas than the average person, but could push it even further to better insure a higher quality result. Keep in mind that in areas of creative pursuit quantity usually leads to quality.
Yes, when you brainstorm you're usually looking for THE idea. But a big part of creativity is simply a numbers game. Generate more ideas and you'll simply have more ideas from which to choose the best. You'll have more good ideas and, sure, more "bad" ideas. But bad ideas can often be fertilizer for the creative process. The best creative thinkers produce more "fertilizer" than most people. (Maybe that's how they got to be great thinkers.)