I used to have to teach this chart and I hated the whole concept. It implies there is some safe or acceptable level of shock and that is just courting disaster. Everyone is different but it is safe to say 100ma (a tenth of an amp) can kill the healthiest person and that kind of current is easily available on just about any fault condition on a line voltage circuit. "Freeze" current, when you can't let go happens right around the high end of a GFCI trip level. Your heart is in danger right then.
