A higher proportion of 16 to 17 year olds (15%) were reported as having a substance misuse problem than those aged 10 to 15 years old (5%).
Adroddwyd bod cyfran uwch o bobl ifanc 16 i 17 oed (15%) â phroblem camddefnyddio sylweddau na'r rhai rhwng 10 a 15 oed (5%).