Where possible to find some suggestions. But does your ask is about ""virus outbreaks"" only and is not about other threats (like harmful or malicious software outbreaks with 'limited' ability to spread)?
I think that if scope is not pinned to certain location -> answer is uncounted.
But what is your task? Does it research and good to receive 'proper' statistics?
Or it is only as gathering some well-known large examples?
And it is only about freshly created (and not re-used or modified ones) harmful items?