The Ministry of Justice does not record data in the form requested. However prison and health records show that in 2009-10:
health services delivered 60,067 clinical interventions for drug addiction in prisons;
CARAT (Counselling, Assessment, Referral, Advice and Throughcare) services performed 66,459 initial assessment for adult prisoners;
10,206 prisoners commenced accredited drug treatment programmes; and
6,586 young people were assessed by the Young People's Substance Misuse Service (YPSMS).
These data are drawn from administrative IT systems and are subject to the inaccuracies inherent in any large-scale assessment and recording system.