No spam - what gives?

I've been running my blog for a number of years. Akismet has killed over 19,000 spam messages over that time. However a few months ago something strange happened - that number stopped changing.

Also, nothing appeared has under spam and no spam comments have been added (legitimate comments have been made) in the last few months either. I seem to have been blessed by the anti-spam fairy and while I'm certain I've not made a pact with the devil, I'm feeling a little freaked by the lack of attention!

Has anyone else noticed this? Any ideas what I've done right?