It is not the correct statistic in my jurisdiction. 15-22 is the statistic cited around here for short term cbt stuff. I would never go near cbt again, so I don't pay much attention or much thought to statistics about it. Often, from what I have read, people go once or twice and decide therapy or the therapist is not for them - but that is different from length of time someone sees a therapist once having decided to keep doing it.