Milter-greylist

Hey -

Is there a good way to check to see how many messages which were delayed by 
milter-greylist which never retried?

I tried counting all instances of "Greylisting in action" from 
/var/log/maillog and then all instances of "X-Greylist" but the figures were 
not what I expected.  I thought there would be more greylist delays then 
accepted messages but I think because I'm on so many really high volume 
mailing lists that wasn't a good idea.

I'm sure there's a fairly simple way to script it but I'm drawing a blank.

Thanks!
Thomas