Since NoSpamNX doesn't provide a history and I haven't followed the numbers, I am not sure how much it has blocked recently. On two blogs where I have it installed I have to manually handle approx. 2 spams a day on the older one and 1 a day on the newer one. Several months ago the amount of spam let through was several times less, perhaps 2 spams a week.
I've thought this is because some spammers or the tools they use have learned to not fill in the do-not-fill field that NoSpamNX and several other anti-spam plugins generate.
For the record, NoSpamNX states having blocked 1503 spambots on the older blog and 908 on the newer one. If I'm replying again to this thread on a later date I'll check if the numbers have changed.
However, those numbers are great, and even if NoSpamNX would be less useful now than it used to be, at least in comparison to other anti-spam efforts, I wish to express my thanks to kubi23 for providing such a great, effortless and errorless anti-spam protection for free for so long. It has been a great ride and I hope it will continue. To this effect I will make a post about adding a new feature that might improve the effectiveness.