One of HBO’s biggest series last year was Westworld, and according to new data from Time Warner, the network’s parent company, it also helped drive a big increase in subscriptions to HBO’s stand-alone streaming service.

Time Warner CEO Jeff Bewkes confirmed during an investors call today that HBO Now had exceeded two million domestic subscribers. By the end of 2015, just eight months after HBO Now launched in the United States, the streaming application had 800,000 subscribers, according to Bewkes. Part of the reason the network is seeing a consistent increase in subscriptions, Bewkes said, is because of original and exclusive series like Westworld and Game of Thrones.

It’s not too surprising that Westworld, one of the most talked about shows that premiered last year, led to growth in subscriptions. The series became the most watched debut season in HBO history, surpassing Game of Thrones and The Sopranos. Much of that success is credited to Westworld being available on HBO Now, allowing viewers with stand-alone subscriptions but who may not have cable packages to watch the episode as it airs.

When HBO Now launched in April 2015, Game of Thrones was in its fifth season. It had already become the gigantic series that it’s known as today, but it didn’t have its start on HBO Now. If that service had launched in 2011, the same year Game of Thrones premiered, there’s no question the series would have easily beaten Westworld for that record title. Still, Westworld managed to bring in 12 million viewers an episode for the entire season, with more than two million live viewers for the finale in December. Game of Thrones’ first season finale did beat Westworld, bringing in just over three million viewers, but averaged 9.2 million viewers over the course of the entire season.

Time Warner CFO Howard Averill commented on the growth in the company’s streaming sector, adding the company will continue to move forward aggressively with what HBO Now offers to subscribers. On the standard network side, Westworld also proved to be a success for the company, helping generate a six percent increase in revenues for the company, coming in at $1.5 billion.

Westworld will return for its second season in 2018. Game of Thrones will return for its seventh season this summer.