Question: The song appearing in the EP, Gold Skies, that reached 21 on "Billboard" was released in what year?
Sentence (from "Animals (Martin Garrix song)"): The track was a commercial success, reaching the top ten or topping on a number of electronic music charts, topping singles charts in the United Kingdom and Belgium, and reached number 21 on the United States' "Billboard" Hot 100.
Relevant evidence: Yes