So out of the 80, we have China responsible for 8, Russia for 2, and 8 other countries responsible for 1 each (?) which totals 18. Financially motivated gangs are responsible for 1/3 or 27. This leaves 35 unaccounted for.
The uncharitable assumption is that those were allocated among Five Eyes (and other Western allies) and Mandiant chose not to (or was not allowed to) identify them. But I'd really like to know if Mandiant has commented on the discrepancy.
Still, the overall conclusion, which I will paraphrase as 'we're doomed', remains valid. Malware as a Service is going to continue to get more popular and probably cheaper.