How many significant figures are in 20 percent?

Just for reference, the question is,

What partial pressure of oxygen is a scuba diver breathing if the total pressure is 6.3 atm and 20 percent of the air is oxygen?

I understand the question and how to solve it and all that
BUT
I am unsure whether there are 1 or 2 sig figs in 20% & whether 20% is considered 0.2 or 0.20.

(After all, I can't find the right answer if I don't know the correct number of significant figures in my answer.)

Thanks!

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