R&B/hip-hop artists have been dominating the charts -- while selling hardly any albums.

For the week ending Jan. 17, A Boogie Wit Da Hoodie topped the Billboard 200 for the second week in a row, selling fewer than 1,000 copies of Hoodie SZN each week. That’s the first and second time ever that a title has hit No. 1 while missing the four-figure mark. Instead, its success was driven almost entirely by streaming, which accounted for 55,000 of its total 56,000 equivalent album units for the week.

Earlier in January, 21 Savage’s I Am > I Was set a record for the smallest weekly sales total for a No. 1 album, selling 3,000 copies. That means that the three lowest sales weeks for a No. 1 album have been for two 2018 hip-hop releases.

That’s not so surprising: Total on-demand audio streams in the United States reached 611 billion in 2018, up 49 percent over the year prior, according to Nielsen Music, while overall physical and digital album sales fell 17.7 percent after a similar decline the year before. With total album-equivalent consumption up 23 percent year over year, streaming gains are outweighing sales losses in terms of units consumed.

Meanwhile, R&B/hip-hop sales are falling much faster than most. Overall sales were down 17.7 percent in 2018, but R&B/hip-hop’s dropped 20.8 percent. As physical sales fell 15.8 percent last year, R&B/hip-hop cratered 27.8 percent. And for the second year in a row, R&B/hip-hop albums dominated the streaming game: In 2018, the genres accounted for an astounding 25.6 percent of album-equivalent audio consumption and 30 percent of all on-demand streams. (Rock, as the No. 2 genre, had 14.2 percent of on-demand streams.)

As R&B/hip-hop streaming leads the pack, album rollout plans are changing. A Boogie’s team, for example, says that it focused on streaming because they knew that was how fans consumed his work. They say they never considered physical copies when creating a marketing plan for Hoodie SZN.

“Nobody does hard copies anymore -- it’s all about streaming now,” says Quincy “QP” Acheampong, CEO of Boogie’s Atlantic imprint, Highbridge the Label. “If Atlantic asked us if we wanted to make hard copies, that wouldn’t even have been an option. Digital is the way to go. We wouldn’t have wasted our time.”

There have been hip-hop and R&B artists who opted for digital-only releases in recent years. Chance the Rapper’s 2016 album, Coloring Book, became the first streaming-exclusive album to chart on the Billboard 200 and to win a Grammy. This year, for the first time since the CD was introduced in the early 1980s, two Grammy album of the year nominees never released physical editions at all: Cardi B’s Invasion of Privacy and H.E.R.’s self-titled release.

Since 21 Savage is also an artist who is heavily consumed on digital streaming platforms, the rapper's team says they relied on their relationships with the streaming services when it came to promoting the album. Like Boogie's team, they say they know their artist dominates on streaming platforms, noting that their job is to meet fans where they are.

“We only did physicals because we were told [by Epic] it was going to make a big impact. We turned in the album early and did physical [copies] just to try something we’ve never done or cared about before,” says Kei Henderson, Savage’s co-manager. “The numbers were so low they were just insignificant. Savage is a streaming artist.”

A version of this article originally appeared in the Jan. 26 issue of Billboard.