Indicate the sources of your data in a note beneath the table or figure. If that is too cumbersome, give the sources in an endnote placed in the text that introduces the table or figure.
Be careful in how you combine data from different sources: are they measuring the same thing, among the same population, across the same time interval? If not, you will want to note any differences in the data or even present them in several tables instead of in one.
Read more on citing data.
Published 7 January 2020