This varied slightly by sex, with the population of females aged 16 to 19 years old increasing by 1.7%, while the population of males increased by 0.9% in mid-2021.
Roedd cynnydd o 1.7% yn y boblogaeth o fenywod 16 i 19 oed, tra bod cynnydd o 0.9% yn y boblogaeth o wrywod yng nghanol 2021.