Key points from this publication are that:
there was a decline from an average daily population of 8,133 in 2011-12 to 7,464 in 2017-18, followed by an increase to a population of 8,197 in 2019-20
there was then a significant fall in the average prison population to 7,339 in 2020-21 due to the impact of the COVID-19 ...