Tops at iTunes

The top singles at iTunes for the week ending March 17.

1. "Happy (From 'Despicable Me 2')," Pharrell Williams

2. "All of Me,"

John Legend, above

3. "Talk Dirty," Jason Derulo, featuring 2 Chainz

4. "Dark Horse," Katy Perry, featuring Juicy J

5. "Let It Go," Idina Menzel