Self Described Religious Identification Survey of U.S. Adults (1990-2001)
Wiccans increased from 8,000 in 1990 to 134,000 in 2001
https://commons.trincoll.edu/aris/surveys/aris-2001/
Interesting PDF list of all religions: https://commons.trincoll.edu/aris/files/2013/11/ARIS-2001-report-complete.pdf