The music industry is obsessed with "new".
The charts discriminate against aging songs; radio stations stake their reputation on premieres; and Ofcom sets quotas for new music on the BBC.
But, for most people, that's irrelevant. There's a reason why the best-selling album in UK chart history is Queen's Greatest Hits; and why second place goes to Abba's Gold.
Research shows that the music of your teenage years is hard-wired into your brain.
There's even something called the "reminiscence bump" - which shows children have superior recognition for songs that date to their parents' and grandparents' teenage years.
And while streaming services fight each other for exclusive new releases, Spotify's own research shows that 40% of songs are streamed more frequently in their second year on the service than their first.
This week, the BPI released data on the "oldies" we played 2017 - showing that songs like TLC's No Scrubs, Toto's Africa and The Temptations' My Girl are still receiving millions of streams.
"Older songs are quietly accounting for a very significant proportion of listening," says BPI analyst Rob Crutchley, who calculates that 30% of the music played on streaming services was released before 2010.
Here are the most popular tracks from each decade.
1940s - Bing Crosby: White Christmas
1950s - Brenda Lee: Rockin' Around The Christmas Tree
Pop stars really do wish it was Christmas every day.
The Pogues are estimated to make £400,000 from the whisky-soaked Fairytale of New York every year. In 2009, Noddy Holder told the BBC that Slade's Merry Xmas Everybody was "definitely a pension plan".
"It was never designed to be that way but it has taken on a life of its own," he said.
According to the BPI, there were more than 160 Christmas songs among the top 15,000 most-streamed tracks of 2017.
Bing Crosby's White Christmas was streamed 8.6m times; while Brenda Lee's Rockin' Around the Christmas Tree notched up 13.9m plays.
But the most popular of all was Mariah Carey's All I Want For Christmas Is You, which jingled and jangled your earholes 26m times.
1960s - The Jackson 5 - I Want You Back
When it was recorded in 1969, I Want You Back was the most expensive single Motown had ever produced - but the gamble paid off.
The five dancing Jackson brothers became stars overnight, scoring four consecutive number ones on the US chart.
Originally called I Wanna Be Free, the song was written for Gladys Knight, but Motown founder Berry Gordy demanded it be re-cast for his new band; and gave their youngest member the lead vocal.
"Michael was 10 years old, but he sang it like a bird," Tito told the Guardian last year.
A funky, vibrant pop classic, it's been sampled by Jay-Z and covered by everyone from Taylor Swift to The Civil Wars... although my personal favourite is this playful, acoustic version by Dutch singer Trijntje Oosterhuis.
In total, 12.6m people listened to the original last year.
1970s - Earth, Wind & Fire - September
"Do you remember / The 21st night of September?"
Well yes, as it happens. That's my wedding anniversary. And if there's a song that's the definition of a wedding disco classic, it's September - an ebullient, horn-driven blast of positivity.
The BPI says its popularity on streaming services last year - with 17.5m plays - might have been triggered by its inclusion on the Trolls soundtrack.
"The association of a song with its usage in a popular film or on TV is often reflected in its play count," said Rob Crutchley.
"In 2017, Guardians Of The Galaxy 2 was one of the most high-profile examples: ELO's Mr Blue Sky and Fleetwood Mac's The Chain - both used in the film - [had] much higher placings than in 2016."
1980s - Wham!: Last Christmas
Another festive favourite, Last Christmas was the subject of a campaign to get it to number one last year, to mark the first anniversary of George Michael's death.
It didn't quite manage it, peaking at number two (as the original did in 1984) but it picked up an impressive 24.2m streams along the way.
The song was written one Sunday in 1984, when the band were visiting George's parents in Hertfordshire.
"We'd had a bite to eat and were sitting together relaxing with the television on in the background when, almost unnoticed, George disappeared upstairs for an hour or so," Andrew told the Daily Mail last year. "When he came back down, such was his excitement, it was as if he had discovered gold. Which, in a sense, he had."
1990s - Oasis: Wonderwall
"I remember strumming the chords and thinking, 'that's quite original,'" said Noel Gallagher, recalling the moment he came up with Wonderwall in a house in Scotland.
"This is probably the first original thing I've ever done."
It's certainly his most popular. Originally titled Wishing Stone, it became Oasis' biggest-selling single when it was released in 1995.
Noel even claims it made him a millionaire four times in one day. "Once for each verse - at 11, three, seven and 11 again at night," he told Man City TV.
The streaming royalties aren't so favourable, though. Wonderwall's 27.4m plays will have earned Noel about £75,000 last year.
2000s - The Killers: Mr Brightside
Nobody bought Mr Brightside when it came out in 2003. It wasn't until The Killers re-released the song a year later that the song caught fire - and it's resisted every attempt to extinguish it since.
The NME's fifth-best single of 2004 racked up its 200th week in the UK charts earlier this year; and its popularity keeps growing. It was streamed 42.2m times last year, up from 26m in 2016.
Not by coincidence, people who were teenagers when the song came out are more likely to use a streaming service than any other age group.
"It's just incredible," Brandon Flowers told me last year. "As fans, we know what that feels like.
"Whether it's Enjoy the Silence from Depeche Mode or Where The Streets Have No Name from U2 - those songs belong to everyone.
"To be a part of it, on the other side of it, it's nothing that we can really explain. But it's really cool."
2010s - Ed Sheeran: Shape Of You... or is it?
No surprises here: Ed Sheeran's third album was so successful that it propelled 16 tracks into the top 20 last March; prompting an overhaul of the chart rules.
Shape Of You went on to become the most-streamed song of all time, with 212m plays (and counting). Of course, it's only natural that as the streaming market grows, current releases will keep breaking records.
Discounting songs released in 2017, the decade's most-streamed track is the sassy club hit You Don't Know Me by Jax Jones and RAYE.
"You Don't Know Me is such a special song to me, so I'm made up," RAYE tells the BBC.
"When Jax and I recorded the track we knew we had something special, but neither of us could have predicted just how big it has become."
"We're very thankful."
Going back further, the most-streamed song of 2010-2015 was Ariana Grande's One Last Time, which became an unofficial anthem of resistance after the Manchester terror attacks.
The song, from her 2014 album My Everything, was played 46.1m times last year.