Pharrell Williams is at the top of the iTunes charts once again.



His catchy single, "Happy," is the No. 1 download on iTunes this week.



Rounding out the rest of the top 5 was John Legend's "All of Me" at No. 2, The Chainsmokers' #SELFIE at No. 3, Katy Perry's "Dark Horse" at No. 4, and Jason Derulo's "Talk Dirty" at No. 5.