A 16 year and 11 months old (male) child
who is 154 pounds (I'm pretty sure it was somewhere around there, we don't use lbs here ;-;)
and is 5 feet and 8 inches tall has
a body mass index of 23.5,
which is at the 75th percentile,
Though these things are fairly inaccurate as they don't count things such as muscle mass and whatnot, if you want a more accurate reading you'd have to go see a doctor/whatever.