What percentage of potentially knowable knowledge do we already know?

Dunningi–Krugeri efect

Johari aken

Donald Rumsfeld, 2002

"There are known knowns. There are things we know that we know. There are known unknowns. That is to say, there are things that we now know we don't know. But there are also unknown unknowns. There are things we do not know we don't know."