Will.i.am and Britney Spears' "Scream & Shout" dips for a second week on the Hot 100, from No. 13 to 15, after debuting at No. 12 two weeks ago. PSY's former seven-week No. 2 Hot 100 smash "Gangnam Style" falls 11-18. And Mariah Carey's 1994 holiday hit "All I Want for Christmas Is You" rises to No. 25 on the Hot 100 after re-entering last week at No. 29. Click through for more chart news about Cassadee Pop and Ellie Goulding.