OK, there are a few exceptions.

About 1.3/6.6 billion (20%) of the world's population.

But I'm not sure whether we should change it as it complicates it a little bit with floats (text field instead of select box, different ways users insert the values...).

If it's possible, yes. The largest group of users in my forum lives in India (GMT: +5:30).

Forum time = GMT.

I see!