What is the average age of potty training?

What is the average age of potty training?
I know every child is different and you should only potty train when they are ready but i didn't know if potty training was generally done when children are around the same age?
My little girl has started pointing to the loo if someone says they want a wee so she is becoming more aware of the need to go to the loo but she is only 16 months old.
When did you start potty training? And how long did it take?
============
industrial training Chandigarh