The "Dirty Dozen" SPAMPIONSHIP: Who needs to kill the most zombies?

From Sophos Naked Security:

The "Dirty Dozen" SPAMPIONSHIP: Who needs to kill the most zombies?

Here they are: the latest "Dirty Dozen" SPAM­PION­SHIP tables, detailing the globe's most dastardly distributors of delinquent data during the first quarter of 2015.