Is it rare for an 18 year old male to have a low testosterone level of 200?

Define "rare" Reference range is set up statistically to include ~96% of "normal" population. So anyone w/level below lower limit of normal means that ~98% of population has higher result. Who cares? More important question than whether it's rare is why it's that low. Also why was test ordered? Perhaps this was a lab error? Clarify above & discuss options w/ordering physician. Repeat test? More tests? Fertility.