Which Enneagram type is most common is not clear. Most of the information available to us today is based on the anecdotal experience of Enneagram practitioners. I am not aware of any scientific studies. It would be hard to do a scientific study because there are too many variables that make up the complexity of personality.

Many Enneagram practitioners have noticed, based on anecdotal experience, the six, seven and nines are most common, at least in North America.