How do you figure out the % units on nutrition labels? For example, how many mg's of Niacin is 6%? If it's based on a 2000 calorie diet I would assume you'd just take 6% of 2000 but that doesn't work out right, the #'s are too high... I know that is probably a "Duh" answer to this but my brain isn't fully functioning yet today. TIA