95% of the universe is dark matter and energy.
Why it is true
Everything we know and see constitutes only 5% of the universe; the rest is invisible and remains a mystery.
Source: Cosmology
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.