How many of us are guilty of insisting our dinner companions watch the latest incredibly hilarious cat video on YouTube while waiting for the appetizers to arrive at the restaurant? It’s got to be a lot.

If you’ve got a smartphone, there’s a very good chance that you’re streaming video. So it won’t startle many people to hear that 81 percent of U.S. smartphone users do just that, according to recently released data from the NPD Group’s Connected Intelligence Smartphone and Tablet Usage Report. This usage is being driven primarily by users who are 25 and younger, who reportedly spend twice as much time watching video content on YouTube and Netflix mobile apps compared to users over the two-decade-and-a-half mark.

Most video streaming occurs over WiFi, but smartphone users do rely on cellular data more than ever. According to NPD, the average U.S. smartphone user consumes close to 3 GB of cellular data per month, with video streaming serving as the top app driving that consumption.

“Users are spending more time watching videos on their smartphones than ever before, as the adoption of smartphones that boast larger displays increases,” Brad Akyuz, NPD connected intelligence mobility practice research director, says. “This mobile streaming behavior is further bolstered by the new offerings of wireless operators, such as T-Mobile’s Binge On and Verizon Wireless’ go90, which run on free sponsored data.”