"The use of custodial sentences for drug offenders increased substantially between 1994 and 2005. The annual number of people imprisoned rose by 111% and the average length of their sentences increased by 29%. Taking into account the rise in the average sentence length (37 months for drug dealing in 2004), the courts handed out nearly three times as much prison time in 2004 as they did 10 years earlier."

Source

Reuter, Peter and Stevens, Alex, "An Analysis of UK Drug Policy: A Monograph Prepared for the UK Drug Policy Commission," UK Drug Policy Commission (London, United Kingdom: April 2007), p. 10.
http://kar.kent.ac.uk/13332/1…