Can data reveal the saddest number one song ever?

When I was 15 I discovered The Smiths, a band whose name had by then long been synonymous with misery. But it was Morrissey's unique style of being miserable – coquettish and laced with Northern English humour, flipping between self-pity and irony – that appealed to my teenage self. I'd always cry at the same points in each song: the end of Hand in Glove, the chord changes before the chorus of Girl Afraid, the line in The Queen is Dead where he sings "we can go for a walk where it's quiet and dry". I'm still not sure why the last one had such an effect. Two decades later, Spotify has built an algorithm that aims to quantify the amount of sadness in a music track.