"We Are Young" tops the 5 million mark in total sales this week. (This counts 149K copies that it sold in the waning weeks of 2011). The song reached the 5M mark in 28 weeks. Only one song in digital history, "Somebody…," has hit 5M faster. It took just 23 weeks. (Wanna know the rest of the top five in reaching 5M the fastest? LMFAO's "Sexy And I Know It" took 34 weeks. Adele's "Rolling In The Deep" took 35. The Black Eyes Peas' "I Gotta Feeling" took 36.)