Depends on what you consider a "circle;" considering the term is technically a shortening of "doujin circle," it's not technically accurate to use the term in reference to western groups in general. Also, you might be surprised at how many Japanese circles only have one member; the term does not necessarily indicate a group, and may be more of a marketing gimmick. I am no expert on the subject, but I believe there are other threads on the forum that have gone into more detail on what the "doujin scene" actually is.