Netflix now makes up a third of all Internet traffic in North America

Netflix makes up 35 percent of downstream Internet traffic during peak hours, according to a new report. Between Netflix, Facebook, YouTube, and other applications, users are downloading about 20 gigabytes of data each month.

It’s a standard ritual: come home from work, make dinner, watch a movie or some episodes of a TV show on Netflix. So many people are enjoying similar evenings, in fact, that video streamed over Netflix now makes up more than a third of all downstream Internet traffic in North America during peak hours, according to a new report from research firm Sandvine.

During the second half of 2014, Netflix streaming made up 35 percent of downstream Internet traffic during the evening, the report says. People are also using more data on their home broadband networks overall, with a typical user now consuming about 20 gigabytes of data each month. Just behind Netflix is YouTube, which makes up 14 percent of traffic on home networks; other popular applications include Facebook, BitTorrent, iTunes, Hulu, and Amazon.

Surprisingly, Netflix also accounts for 9.5 percent of all upstream traffic – data sent from users’ home connections to servers – during peak hours. That’s because Netflix relies on Transmission Control Protocol (TCP) to connect customers with its servers, and TCP uses acknowledgement messages sent from the client to let the host know that data has been successfully received. All those acknowledgement packets add up to quite a bit of data – so much so that upstream traffic can sometimes interfere with downloads, especially on broadband connections for which upload speeds are much slower than download speeds.

Sandvine’s report also looked at mobile Internet traffic, which was led by YouTube and Facebook, with about 20 percent and 19 percent of traffic respectively. Facebook’s share of traffic on both fixed and mobile connections has skyrocketed since September, when it added a feature to automatically begin playing videos in users’ News Feeds. A typical mobile user consumers 118 megabytes of data each month, up from 102 megabytes last year, Sandvine says.

Netflix’s commanding share of Internet traffic has put it at odds with Internet Service Providers such as Verizon and Comcast, who say Netflix overwhelms their networks with traffic and that the company should have to pay for all the bandwidth it uses. Earlier this year, Netflix paid undisclosed amounts of money to both Verizon and Comcast in exchange for being able to interconnect directly with their networks, resulting in speedier streaming for customers. If Netflix’s share of traffic continues to increase year over year, it will put the company at the center of more debates about network congestion and the relationships between content companies and ISPs.