That's a really good question. I actually don't think it has been terribly common, much as the House of Commons over its entire history has thrown out only four members—one of them twice, I believe. Along the same thinking, this is not something where we're going to see members of Parliament or senators losing pensions left, right, and centre. Actually, if anything, it is a deterrent. If individuals are found guilty, they will lose a pension, but I don't believe you'd find probably more than a dozen or two examples. I'd be surprised if you found more than a dozen over the last 10 or 20 years, as you suggested.
On September 30th, 2014. See this statement in context.