What is the longest - running number one single in New Zealand since Smashproof 's song " Brother " .
It topped the 7 million downloads mark in the United States in July 2012 , becoming the second fastest song in digital history to reach this plateau ( in 68 weeks ) just behind Adele 's " Rolling in the Deep " which achieved it in 67 weeks , and the third - biggest selling digital single since Nielsen SoundScan began tracking digital sales in 2003 .