Although the USA does not ask for religion information on its federal census, many countries do. Here are the results from a few of them:
According to the 2001 Australian Census, there were 8755 people who self-identified as witches and 10,632 who self-identified as Pagans. Australia has a population of approximately 20 million. More info
According to the 2001 Canadian Census, there were 21,085 people who self-identified as pagans in Canada (approximately equal number of males and females). Additionally, there were 300,345 who identified as Buddhist, 297,200 who identified as Hindu, 278,410 who identified as Sikh, 37,550 who identified as Eastern Religion, and an additional 42,805 who identified as other religions which could be considered Pagan. That's 977,390 people who fit into the broad umbrella category of Pagan in Canada, a country with a population of 29,639,035. This means that 1 in 30 Canadians identified as a member of a Pagan religion and that there are only 22 Christians for every Pagan in Canada. More info
1,537,260 people in England and Wales selected a non-Abrahamic religion on the 2001 census. England and Wales had a total population of 52,041,920 in 2001. More info
23,529 people claimed a religion other than Christian, Buddhist, Hindu, Jewish, Muslim, Sikh, Bahai, Satanist, or Rastafarian. (which by some definitions are the non-Pagan religions) There were 5,564 Hindus, 6,572 Sikhs, 6,830 Buddhists, meaning that 42,495 of the 5,062,011 people in Scotland meet the broader classification of Pagan. More info
New Zealand's 2001 census found 39,798 Hindus, 41,634 Buddhists, 16,062 Spiritualists and followers of other New Age Religions, 5,196 Sikhs, 1,998 follower of Maori Religion, 1,488 Theists, 1,272 practitioners of Chinese Religions, 483 Zoroastrians, 303 practicioners of Japanese Religions, and 57 Jainists. This totals 108,291 Pagans. There were 3,468,813 people in New Zealand as of the 2001 Census. More info