Pitbull ft. Ke$ha's anthem about having the night of your life, "Timber", has been on the Billboard charts for 15 weeks now. And for the past two weeks, it's stayed strong at the no.1 position on the Billboard Hot 100 chart. Seeing Ke$ha is currently in rehab managing her eating disorder, it's great news that as she's bettering herself, one of her songs is currently #1 in North America. Congratulations to the pair! Coming in at number 2 on the Billboard Hot 100 is Katy Perry ft. Juicy J's bouncy single "Dark Horse", off Perry's latest album Prism, while the no.3 spot goes to OneRepublic's catchy jam "Counting Stars". Indie-rock newcomers A Great Big World owe a lot to Christina Aguilera, who personally called up the duo to re-record their song "Say Something", and now the track is at #4 on the charts. Coming in at number 5 is Eminem ft. Rihanna's "The Monster", who was at no.1 just shy of three weeks ago.