Facebook CEO Mark Zuckerberg said today that the social network’s users view more than 4 billion videos a day. In September than number was just one billion, and in January, it was 3 billion.

Sheryl Sandberg, the company’s chief operating officer, said that 75 percent of all video views were on mobile devices.

Zuckerberg’s comments came as part of the company’s quarterly earnings call this afternoon. Today, the company said it had brought in $3.54 billion in revenue and a non-GAAP earnings per share of 42 cents. The results showed Facebook’s increasing success on mobile. All told, 73 percent of its $3.32 billion in ad sales came from mobile ads.