% of HP to go into the hospital?

What %HP do you go into the hospital, and become non-attackable?
It asks me if i want to heal at around half, but i am just wondering where the cut off is for hospital vs death.

 

i believe its if you drop below 20% of your health you become unattackable

 

Thank you very much,so 20 is the magic number. Now to raise my HP enough so that 20% of it is greater than what others within my lvl range can do in an attack. If i am not listed, i do not wanna be killed!

 

You can still be hitlisted and killed even if you are in the hospital..

 

yes 20% you cant be normal attacked.can be listed still no matter what unless dead.