I think the consensus is that most of us use %10 or less, and that Einstein and his ilk probably use about %17...but recent findings about "brain plasticity" show why that may be so...it would seem at first that "the balance" is wasted, but it seems to me it's there as a sort of "back up" when areas of the brain are damaged, and other areas are called on to compensate...when I lost so much of my "short-term" memory, as it is commonly called (though it's actually "working memory" which we maintain until it goes into long-term memory..strictly speakiing, "short term memory" lasts a matter of a few seconds or the time it takes the brain to process stimuli). But I will "revisit" this question after a little research to refresh my memory!