Spotify had a considerable head start on Apple when it came to its subscriber base, but the music service from the Cupertino company is closing in on its competition. Apple Music now has more than 20 million subscribers, according to a report from Billboard.

Apple’s streaming music service reached the new milestone just 18 months after its initial launch. The company saw a significant jump in subscribers in the last three months, increasing its paying members by 15 percent since it reached 17 million subscribers in September.

According to the company, 60 percent of customers streaming on Apple Music have not bought content from the iTunes Music Store in the last 12 months—a statistic that is likely exciting for Apple and disappointing for artists who get a larger profit from purchases than from streams.

Much of Apple’s success has been driven by its exclusive content. During 2016, the platform got the initial launch of chart-topping albums including Drake’s Views, Frank Ocean’s Blonde, Major Key from DJ Khaled, Birds in the Trap Sing McKnight from Travis Scott, and Chance the Rapper’s Coloring Book, among others.

Many of those titles hit milestones on Apple Music. Drake’s Views was the first album to achieve one billion streams on the platform, while Chance’s album reached the top 10 of the Billboard charts on streams alone—a feat Apple's senior vice president of internet software and services Eddie Cue told Billboard he “can't recall that being done before.”

Apple has made up significant ground in the streaming market since launching at essentially zero in 2015, but it’s still trailing Spotify. In fact, it’s trailing by about as much as it was at launch.

Back in 2015, as Apple was just arriving on scene, Spotify had 20 million subscribers. Now as 2016 comes to a close, Spotify is still ahead of Apple Music by 20 million subscribers, as the streaming service announced it surpassed the 40 million paid users mark in September.

2017 is sure to bring a fierce competition between the top streaming services, as Apple and Spotify battle for exclusive rights and hope to solidify their subscriber bases.

Despite trailing in paid users, Apple may be at an advantage compared to Spotify thanks primarily to the bigger business backing Apple Music. The Swedish startup has managed to up its dues paying members and its revenue, but continued to hemorrhage money, finishing 2015 nearly $200 million in the red.

It’s unclear how long that model will be sustainable for Spotify, especially when its primary competition is one of the richest companies in the world.