The data also showed a rise in the number of people in prisons (4,000, 7.2% in 2021 from 3,000, 4.8% in 2011) which is largely due to the opening of a new prison (HMP Berwyn) in 2017 in Wrexham.
Roedd y data’n dangos hefyd y bu cynnydd yn nifer y bobl mewn carchardai (4,000, 7.2% yn 2021, o 3,000, 4.8% yn 2011).