Behind this obscure title lies a treasure of information and data concerning religious groups in the world. Conducted by the Pew Research Center, here are some of the most interesting findings:

About one of every six people worldwide has no religious affiliation. This makes the “unaffiliated,” as the study calls them, the third-largest group worldwide, with 16 percent of the global population — about equal to Catholics.

The study also found a wide disparity in the median age of religious populations, with Muslims and Hindus the youngest, and Buddhists and Jews the oldest. The median age of the youngest group, Muslims, was 23, while the median for Jews was 36.

Over all, Christians (including Catholics) are the largest religious group, with 2.2 billion people, about 32 percent of the world’s population. They are followed by Muslims, with 1.6 billion, about 23 percent. There are about one billion Hindus, about 15 percent of the global population, and nearly half a billion Buddhists, about 7 percent.