Is the pull-out method reliable?

My husband and I use the pull-out method, sometimes condoms. Mostly the pull-out method, we've been using the pull-out method for 3 years now. I would say it works. We don't want baby #2 just yet but we want to be prepared when we're ready to try. No birth control. Also, everytime (not very many) he pulled out too late or just simply forgot to pull out, I would take Plan B. We had 4 mishaps in a 3 year period. I'd say we're good. If we were to use pull-out method all the time, what are the chances of pregnancy?