The Pew Research Center for the Religion and Public Life Project compares religious diversity in different parts of the world in this map.
You can immediately see, for example, that Canada is more diverse than the United States, as is parts of Asia and the Pacific.
The study focused on the five major religions, Buddhism, Christianity, Hinduism, Islam and Judaism which, the Pew Center notes, make up over 3/4 of the worlds population.
The chart below shows the degree of religious diversity by region. Asia Pacific is the most diverse while the Middle east is the least.