90% of the world's emails are spam.
Why it is true
The overwhelming majority of daily email traffic consists of unsolicited messages, scams, misleading advertising, or malware.
Source: Internet Statistics
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.