NEW YORK • This year, 12 songs reached the top of the Billboard singles chart, known as the Hot 100, from Ed Sheeran's meticulously constructed Shape Of You to Cardi B's casual Bodak Yellow (Money Moves).
The track with the longest run atop the heap - Despacito, by Luis Fonsi and Daddy Yankee, featuring Justin Bieber - was sung almost entirely in Spanish.
On the album side, there were No. 1s by Future (with two different LPs in back-to-back weeks), the revitalised LCD Soundsystem, the little-known rapper NF and, of course, heavyweights such as Katy Perry, Pink and Taylor Swift.
In other words, the monoculture had so many disrupters that cultural whiplash became the new normal.
The most obvious explanation was that the newfound dominance of digital streaming scrambled the entrenched hierarchies.
With physical and digital album sales as well as track downloads all in free fall, and hip-hop and R&B setting the pace for streaming, major labels and major stars were often left scrambling to earn the honours that once came so easily.
Because the rules and norms of this era are still coalescing, the systems could also be gamed. Loyal listeners schemed to get their favourites recognised, while sly marketing efforts tried to put a heavy thumb on the scales.
In all, the machinations made for one of the most disorienting and often exhilarating years of hit music in recent memory. Below are some of the trends, tricks and standout moments. RAP AS INDUSTRY LEADER Nothing streams like a rap banger. And nothing could motor a song up the charts this year - aside from event-releases from Sheeran, Swift and Bieber - quicker than a tonne of Internet-driven chatter.
Using a sample week last month, Nielsen found that streaming was up 59 per cent year over year, with 80.5 per cent of all music consumption now happening digitally.
The biggest beneficiaries were rap stars with loyal followings: Building on the meme-driven success of Rae Sremmurd's Black Beatles, Migos' Bad And Boujee hit No. 1 in January as "raindrop/drop top" jokes became a Twitter sensation.
Other rap smashes to score big this year - with or without Top 40 radio support, which often came later, if at all - included Kendrick Lamar's Humble, DJ Khaled's I'm The One and Post Malone's Rockstar.
MAKING THE STREAMS COUNT
Sometimes, a grassroots push, such as the loosely organised social media campaign to vault Cardi B over Swift's Look What You Made Me Do, was not quite enough. In the case of Rockstar, which was a smash on Spotify and Apple Music immediately upon release, Post Malone also got a wily assist from his label, Republic Records, which found a loophole on YouTube.
Free streams on YouTube count towards Hot 100 placement. But instead of posting the entire song free, Republic uploaded a version of Rockstar that was exactly the same length as the actual track, but featured only its chorus, looped again and again. (It also closed comments on the video, preventing users from explaining to others what was going on.) In its first few weeks, the video earned more than 40 million plays, contributing to the song's reign on Billboard's Streaming Songs chart, which preceded its peak on the Hot 100.
The successful tactic even had copycats - Big Sean's Pull Up N Wreck, for one - though YouTube has since had the videos removed and changed its rules, telling Pitchfork that "any upload of a song intended to mislead a user (preview, truncated, looped) posted on YouTube to look like the original song will not contribute to any charts".
It may not work for everyone. But for Swift, like Adele before her, this year was not yet time to follow the flock. By keeping her new album, Reputation, off streaming services for its first three weeks, Swift guaranteed herself an old-fashioned blockbuster, selling 1.2 million copies in her debut week.
ALBUMS AS ADD-ONS
Although it has been around for a decade, the strategy gained prominence this year as Pink, Perry, LCD Soundsystem, Arcade Fire, Kenny Chesney, Shania Twain and U2 topped the album chart in part by including copies of their new releases with the purchase of concert tickets.
THE REMIX COMES THROUGH
The big-name remix - another tried-and-true manoeuvre that found new relevance this year - breathed extra life into a few big hits.
Despacito, the pop-reggaeton game-changer, was already huge, especially on YouTube and the Spotify global chart, before Bieber's verse was added.
But the remix made it a supernova that led the Hot 100 for a record-tying 16 straight weeks and earned Grammy nominations for record and song of the year.
Beyonce provided a similar bit of magic to J Balvin's Mi Gente, lifting it up to No. 3 from No. 21. She later jumped on Sheeran's Perfect, taking it all the way to No. 1.