How to know which blogs of a multisite have a lot of comments?

I am currently administrating a multisite platform with more than 1000 active bloggers.

I have typepad antispam plugin activated for all users, but some bloggers don’t enter their API and sometimes I find some blogs with thousands of comments and being spammed heavily.

I know about captcha, but even if I add another plugin to control spam, is there any way to display what blogs have a lot of comments?

In the multisite admin I can’t really see a way to display what blogs have a lot of comments or to order blogs with number of comments.

Thanks!