The average cord cutter—a person who watches online video instead of subscribing to a cable TV package—isn't all that far away from going over the typical data usage limits enforced by Internet service providers.

Not all ISPs enforce caps. But Comcast, the nation's largest broadband provider, is rolling out 300GB monthly limits in parts of its territory with $10 charges for each additional 50GB. Time Warner Cable, which Comcast is trying to acquire, offers an optional plan with a measly 30GB cap in exchange for a $5 monthly discount, but almost everyone sticks with the unlimited plan.

Sandvine's latest Global Internet Phenomena report released today, based on measurements in March, says that Internet users in the United States who appear to be cord cutters "consume on average 212GB a month, more than seven times the usage of a typical subscriber. These 'cord cutters' consume an average of 100 hours of video a month and account for 54 percent of total traffic consumed each month."

Across all US Internet subscribers, about 6 percent use more than 200GB a month. The top 5 percent of online video watchers are hitting an average of 328GB a month, Sandvine said. This number represents total data usage, including both upload and download on fixed networks; the data does not include cellular Internet.

Sandvine sells equipment that helps consumer broadband providers such as Comcast manage network congestion. Its reports are based on anonymized data from "a selection of Sandvine’s 250-plus communications service provider" customers across the globe.

The Sandvine data doesn't actually show whether users subscribe to a traditional pay-TV package. Instead, the company classifies the top 15 percent of streaming audio and video users as subscribers who "exhibit 'cord cutting' behavior."

"The most striking fact of all may be the revelation that the top 15th-percentile of video users actually consume the majority of monthly network traffic, and that the bottom 15th-percentile of users consume only 0.5 percent," Sandvine wrote.

For the top 15 percent, 153GB out of the 212GB total is composed of audio and video.

What about the top 5 or top 10 percent? The report doesn't cover those percentiles, but a Sandvine spokesperson provided the data to Ars. The top 5 percent uses an average of 328GB a month, with 250GB of that coming from streaming audio and video. The top 10 percent uses an average of 247GB a month, with 182GB coming from streaming audio and video.

Sandvine estimated that the top 15 percent of subscribers watch an average of 100 hours of video by using Netflix's bitrate levels and assuming an equal share of high- and standard-definition video. "That may seem like a shockingly high number to some, but in homes with multiple individuals, and multiple screens, it is a number that is quite easily achievable," the report said.

This chart from Sandvine compares apparent cord cutters to "typical subscribers" between the 15th and 80th percentiles and "non-streamers" in the bottom 15 percent:

Netflix now accounts for 34.21 percent of North American traffic at peak viewing periods, up from 31.62 percent in the second half of 2013. YouTube is second at 13.19 percent, down from 18.69 percent in 2H 2013 and 17.1 percent in 1H 2013.

Netflix's share is apparently due to its increased use of "Super HD" videos, which Sandvine said can be "up to 50 percent larger than the previous 1080p content."

Sandvine said it doesn't know why YouTube dropped so much, but the company cautioned not to read too much into the fluctuation unless it continues in the next half of the year.

On cellular networks in North America, YouTube is king at peak download times, while Facebook is #1 for uploads:

Overall usage for North American mobile users jumped from an average of 390.1MB to 443.5MB between September and March. "Median usage, a figure we feel is more indicative of a 'typical user,' grew at an even faster pace by over 43 percent from 58.7MB to 84MB," likely reflecting increasing use among first-time smartphone owners, Sandvine said.

The busiest 1 percent of subscribers account for 18.6 percent of upstream mobile traffic and 11.5 percent of downstream mobile traffic.

Here are some other tidbits from a press release accompanying the latest Sandvine report: