Here's one to challenge your percentages
New Scientist carried a somewhat speculative article recently (I read it today at work as I am so busy yawn yawn)
Anyway this article reckons that DNA carries a load of (so called) junk code which they are ascribing to memory. In the body it is anti-body memory (immunity info), in the brain it is long-term memory and in sperm (no you can read the article for yourself if you don't believe me) it stores something else.
It is well known that the brain/body barrier blocks anti-bodies and drugs.
most of our brain capacity is tied-up in waking hours in motor actions and visual processing. So we only use a small percentage to think with but the rest is ACTIVE all right, or we would fall over. I rest my case, (and my body).