Within the flow of text, punctuation marks are used to separate large numerals (in the thousands or higher), and for fractions (use 0 in front of a fraction less than 1, e.g., 0.25). Which punctuations symbols to use depends on whether you are using British or American English, and different fields of study may have different standards. Usually there is no space between a percentage sign and a numeral.
The population of Uppsala is around 200,000 people, which is about 2.22% of Sweden’s population. [American]
The population of Uppsala is around 200.000 people, which is about 2,22% of Sweden’s population. [British]