Prominent groups within this Traditional Witchcraft revival included Andrew Chumbley's Cultus Sabbati and the Cornish Ros an Bucca coven. Originating in Britain, Wicca then spread to North America, Australasia, continental Europe, and South Africa. The actual number of Wiccans worldwide is unknown, and it has been noted that it is more difficult to establish the numbers of members of Neopagan faiths than many other religions due to their disorganised structure. However, Adherents.com, an independent website which specialises in collecting estimates of world religions, cites over thirty sources with estimates of numbers of Wiccans (principally from the USA and the UK). From this, they developed a median estimate of 800,000 members. As of 2016, Doyle White suggested that there were "hundreds of thousands of practising Wiccans around the globe". In 1998, the Wiccan high priestess and academic psychologist Vivianne Crowley suggested that Wicca had been less successful in propagating in countries whose populations were primarily Roman Catholic. She suggested that this might be because Wicca's emphasis on a female divinity was more novel to people raised in Protestant-dominant backgrounds. On the basis of her experience, Pearson concurred that this was broadly true. Wicca has been described as a non-proselytizing religion. In 1998, Pearson noted that there were very few individuals who had grown up as Wiccans although increasing numbers of Wiccan adults were themselves parents. Many Wiccan parents did not refer to their children as also being Wiccan, believing it important that the latter are allowed to make their own choices about their religious identity when they are old enough. From her fieldwork among members of the Reclaiming tradition in California during 1980-90, the anthropologist Jone Salomonsen found that many described joining the movement following "an extraordinary experience of revelation". Based on their analysis of internet trends, the sociologists of religion Douglas Ezzy and Helen Berger argued that, by 2009, the "phenomenal growth" that Wicca has experienced in preceding years had slowed. From her 1996 survey of British Wiccans, Pearson found that most Wiccans were aged between 25 and 45, with the average age being around 35. She noted that as the Wiccan community aged, so the proportion of older practitioners would increase. She found roughly equally proportions of men and women, and found that 62% were from Protestant backgrounds, which was consistent with the dominance of Protestantism in Britain at large.