Wales has the highest imprisonment rates in Western Europe according to new research by Cardiff University.
England and Wales are known to have the highest rates in Western Europe but this study is the first to analyse the two separately.
It found that a higher proportion of Wales' population was serving time in prison than in England.
In 2017, there were 154 Welsh prisoners per 100,000 of the Welsh population. In England the rate is lower with 141 prisoners per 100,000 of the population.
The number of prison sentences handed out in Wales between 2010 and 2017 rose by 0.3% whilst in England, during the same period, they fell by 16%.
However, custodial sentences in England are longer at an average of 17.4 months compared to 13.4 months in Wales.
The report also showed levels of racial disproportionality are also higher in Welsh prisons with white prisoners receiving the lowest average sentence length and black prisoners receiving the longest.
Dr Robert Jones from the Wales Governance Centre at Cardiff University, who put together the research said it was important to look at England and Wales separately.
The Ministry of Justice agree the prison population is too high and say they are exploring alternatives to custody but are "clear that prison will continue to be the best place for serious offenders.”