As has been pointed out already, most cases are unreported. Look at it this way, if you had WEP you could well figure that you won't be cracked.
How would most even know if you had? How would most users know, would they even care to ever look at a log?
It doesn't take a prosecution and publication to prove that it has happened now does it or is that what you need?
BTW, I'm genuinely interested if you or anyone else can find my powerstrip branded Borl "Made in England". Seriously. 4 and 6 way versions available.
David.