I've done a bit of research. Out of all of the pardons granted in the last 10 years, more than 50% of the pardons are granted to people who have been convicted of one of three offences: a Narcotic Control Act offence, which would include marijuana possession and similar crimes; impaired driving; or low-level assault. Does that jibe with your understanding of the statistics?
On November 17th, 2010. See this statement in context.