A citation is a reference to a document where information came from in the first place. What document are you expecting to be cited here? A citation for some internal Facebook email where a manager asked for a stat and the data guys responded with a number? How's that going to help you if it's just the same number as in here?

If I tell you I saw a cat in my garden, and you demand 'citation needed', what do you want me to cough up? There's no document to cite. That's just me telling you what I saw.