Scientology about the same as satanism and heathenism ...
... in terms of number of adherents, according to the 2011 Census in England and Wales. http://www.ons.gov.uk/ons/dcp171778_290685.pdf
2418 Scientologists [also 379 Eckankarists]
Pagans and Wiccans way out ahead with 56620 and 11766 respectively. Druids 4189.
Moonies only 452.
Jedi Knights 176632. Heavy Metalists 6242.
Heber Jentzsch used to say there were 8 or 9 million scientologists, I think. Then Tommy Davis came along and said the church had grown more in the last 5 years than in the previous 50. Which, if it means anything, would suggest >16 million scientologists. So where are they? Not in England or Wales apparently. Maybe in some other sector of the galaxy.