Esports is becoming a big deal in driving online video traffic. Market researcher Newzoo said today that esports drives 21.3 percent of viewership on livestreaming site Twitch, which has grown to more than 100 million viewers a month.

And while Twitch’s creation of a market of game spectatorship is often credited for the dawn of esports, there’s plenty of evidence to show that esports is helping Twitch grow even more massive. Newzoo estimates that fans watched 475.5 million hours of esports content across all franchises from July 2015 to December 2015. The average viewing time was 79 million hours per month.

Newzoo said the share of esports content compared to game content streamed by consumers varies widely from 12.7 percent for Hearthstone to 51.9 percent for Dota 2. That’s why you see Twitch continuoing to create esports partnerships such as the recent deals with Psyonix’s Rocket League and Super Evil MegaCorp’s mobile multiplayer online battle arena game Vainglory.

Meanwhile, MOBAs and shooters account for 85 percent of the time spent viewing esports on Twitch. MOBAs alone account for 58 percent of the total hours watched on Twitch. And most of that comes from Riot Games’ League of Legends and Valve’s Dota 2. Combined with shooters (primarily Valve’s Counterstrike: Global Offensive), the two genres racked up 406.7 million hours of watched esports content in the second half of last year.

Image Credit: Newzoo

About ten percent of the hours watched went to streams in the strategy genre. These streams include Age of Empires II: The Conquerors, StarCraft II, and Hearthstone. Consumers watched a combined 47.3 million hours of strategy esports content in the last six months of 2015.

Other things that drive channel views, and Twitch traffic on a whole, are large events such as esports tournaments. In the week of the March 2 to March 6, ESL organized one of the biggest esports events, IEM Katowice. During the event, viewership for CS:GO doubled to almost 400,000 viewers, and at one point during the finals, it spiked at 525,000 viewers.