"Inmates were sentenced mainly for the following types of criminal offences: drug offences (18%), theft (16%), robbery (14%), and homicide (12%)."

Source

Aebi, M.F. & Delgrande, N. (2015). SPACE I – Council of Europe Annual Penal Statistics: Prison populations. Survey 2013. Strasbourg: Council of Europe, p. 2.
http://www3.unil.ch/wpmu/spac…
http://www3.unil.ch/wpmu/spac…