@feruze-- I agree with you that it's important to know about demographics, but I don't think that this information is enough because demographics actually change pretty quickly. Just in the next couple of decades, researchers are expecting some important differences in world demographics.
For example, it is said that by 2025, the world will be largely populated by Chinese and Indians. Islam is expected to become the world's largest religion by that time and the largest age group is supposed to be those over 65 years old.
So it's not enough to know current demographics, we also need to be able to make educated guesses about the near future and what changes will take place. Demographics is incomplete without additional research in my view. It's necessary to know what world religion demographics are for example, but we also need to know which religion is the fastest growing to understand what the world will look like in several decades.
What do you think?