Countries with the most botnets

A colleague needs to know, along with citable sources if possible.

Ideally - number of zombified PCs, percentage of zombified PCs, name of
nation, source.

Threat reports from symantec and macafee suggest the US leads, with
China a very close second.

Yes, we realize that answers will be imperfect.

    --Steve Bellovin,

The Conficker data would be one empirical source you can look at. You have a
break down by ASN and Country:

Team Cymru seems to put out a lot of information in their newsletters
about where bots are, e.g. this article about the locations of botnet

The CBL has stats too - - total spamtrap flow - by country (india leads the pack yay?) - by ISP

Data is of course needed as a starting point. But does anyone have anything to explain differences between countries, industries, some other distinction, if any? Although we use terms from biology, i.e. infection, virus, etc; bots aren't naturally occuring phenomena.

Or even in small communities, do universities have differences between themselves? Resnets vs faculty? Engineering vs arts & sciences?