2015's biggest songs, according to Instagram12/18/2015December 18, 20151. What Do You Mean, Justin Bieber | 2. Good For You, Selena Gomez | 3. Hello, Adele | 4. She's Kinda Hot, 5 Seconds of Summer | 5. Blank Space, Taylor Swift | Source: InstagramCopy linkImage: Reuters/A. GarofaloAdvertisement
