The SAPS maintain detailed statistics on crime per annum, disaggregated by province and type of offence. These statistics are released once a year.
Visit the SAPS stats page here (2004 – 2012 crime stats)
SAPS 1994 – 2004 crime stats (PDF download)
The Department of Correctional Services maintains detailed statistics on their website regarding the inmate population. These statistics are typically updated every 3 months or so.