This site shows how common your surname is around the world (actually a quick look at the FAQ reveals that only 22 countries are covered). Anyway, I pumped Pott in and found out that:

• Pott is most common in Germany with 62 people per million (pretty rare)
• In Manitoba, Canada 88 people per million have the surname Pott
• The most common first name for Potts is Lothar!

Pott is most common in Germany although there appear to be quite a few Potts in Canada too

The highest density that I could find was Murphy in Ireland with 17,080 people per million!