More from Pew:

Adherents of the world’s two largest religious groups, Christians and Muslims, who together comprise more than half of the global population, were harassed in the largest number of countries. Over the three-year period studied, incidents of either government or social harassment were reported against Christians in 130 countries (66%) and against Muslims in 117 countries (59%). Buddhists and Hindus – who together account for roughly one-fifth of the world’s population and who are more geographically concentrated than Christians or Muslims – faced harassment in fewer places; harassment was reported against Buddhists in 16 countries (8%) and against Hindus in 27 countries (14%).

In proportion to their numbers, some smaller religious groups faced especially widespread harassment. Although Jews comprise less than 1% of the world’s population, government or social harassment of Jews was reported in 75 countries (38%). Incidents of harassment involving members of other world religions – including Sikhs, ancient faiths such as Zoroastrianism, newer faith groups such as Baha’is and Rastafarians, and localized groups that practice tribal or folk religions – were reported in 84 countries (42%).

In addition, the study finds that restrictions on religion are particularly common in countries that prohibit blasphemy, apostasy or defamation of religion. While such laws are sometimes promoted as a way to protect religion, in practice they often serve to punish religious minorities whose beliefs are deemed unorthodox or heretical.

Again, this is surprising--why are the largest religious groups most often the victims of persecution? "Because there is more of them" is not a satisfying answer, since perspectives on harassment and prejudice often suggest that it it works only from the majority toward the minority. I suppose that since Christians comprise about a third of the world's population it is possible that they are a minority in all 130 of the countries where they faced persecution. But if simple minority status makes one subject to persecution, we would expect to observe this with much greater frequency for groups like Jews, Buddhists, or Sikhs.

This deserves further exploration but I'm not sure exactly what direction to go with it at the moment, so please leave comments with your thoughts. One possibility is that tricky little caveat in the fine print that these counts don't address how severe the persecution was. Other suggestions or observation are welcome.