Image copyright Columbia / Capitol Records Image caption Two of 2019's most played duos: Sam Smith with Normani, and Calvin Harris with Rag 'N' Bone Man Calvin Harris had the most-played song on UK radio last year with the triumphant dance anthem, Giant.
Like the majority of his 39 chart hits, it featured a guest vocal - in this case from gravel-voiced blues singer Rag 'N' Bone Man.
The Scottish producer has previously collaborated with Rihanna, Dua Lipa and Dizzee Rascal, and the music industry is increasingly following his formula.
Collaborations accounted for 40% of radio's most-played songs in 2018.
That's up from 5% in 2008 and 22% in 2017, according to music royalty body PPL, which monitors the music played on TV and radio; and in pubs and clubs.
It said that four most popular songs on UK radio last year featured two or more artists, including Sam Smith and Normani's duet Dancing With A Stranger and Ed Sheeran and Justin Bieber's summer anthem I Don't Care.
Most-played songs of 2019 (Source: PPL) Title Artist 1) Giant Calvin Harris & Rag 'N' Bone Man 2) Nothing Breaks Like A Heart Mark Ronson Feat. Miley Cyrus 3) Dancing With A Stranger Sam Smith & Normani 4) I Don't Care Ed Sheeran & Justin Bieber 5) Just You And I Tom Walker 6) Higher Love Kygo & Whitney Houston 7) Sweet But Psycho Ava Max 8) Someone You Loved Lewis Capaldi 9) Don't Call Me Up Mabel 10) Walk Me Home P!nk The trend looks set to continue in 2020: More than half of this week's top 40 singles (52.5%) are credited to multiple artists.
So why are musicians teaming up so often? There are several reasons.
First of all, the way that artists are credited has changed. When Michael Jackson roped in Eddie Van Halen to play the guitar solo on Beat It, his name didn't appear on the front sleeve or the disc itself. By the time he released Give In To Me in 1991, Slash not only had his photo on the cover, but he received a "featuring" credit on the charts.
That practice has only accelerated as hip-hop, traditionally the most collaborative branch of music, has become the world's most-listened to genre.
Separately, artists have become adept at "gaming" playlists on streaming services like Spotify and Apple Music by creating multiple versions of the same song featuring star guests.
Image copyright Atlantic Records Image caption Ed Sheeran and Justin Bieber combined their star power on the carefree summer hit I Don't Care One of last year's biggest hits, Old Town Road by Little Nas X, had six remixes that helped it span genre-based playlists like country (with Billy Ray Cyrus on guest vocals), K-pop (featuring RM from the boyband BTS) and dance music (in collaboration with Diplo).
The side-effect is that collaborations can bring new audiences to an existing song. That's why Doja Cat's smash hit Say So has recently been re-recorded with a guest verse from Nicki Minaj; and Megan Thee Stallion's Savage now comes with added Beyoncé.
Staggering the release of these remixes also helps a song sustain its presence on the charts and popular streaming playlists - making more money for the artists concerned.
The power of combining two (or more) big names also helped Ed Sheeran become the most-played artist on the UK's airwaves last year.
His latest album, the No. 6 Collaborations Project, featured no fewer than 22 other artists, from Eminem and Stormzy to Chris Stapleton and Bruno Mars.
He has now topped the UK's airplay chart four times in the last five years - with Coldplay briefly breaking his run in 2016.
Most-played artists of 2019 (Source: PPL_ 1) Ed Sheeran 2) Calvin Harris 3) Sam Smith 4) Jess Glynne 5) P!nk 6) George Ezra 7) Rita Ora 8) Little Mix 9) Coldplay 10) Maroon 5 The PPL noted that eight of the top 10 most-played artists were British, a figure that has remained constant for three years.
The charts were revealed as part of its annual report, which announced that the society had collected £271.8 million on behalf of 108,000 performers and rights holders over the last year.
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