A study last month found that pop music is sadder now more than ever, and it's because top 40 artists are opting for slower tempos and minor keys, as you can see from this new interactive by WNYC's John Keefe.

The study by Glenn Schellenberg and Christian von Scheve looked at top 40 singles in the past five decades. They found "an increase in the use of minor mode and a decrease in average tempo, confirming that popular music became more sad-sounding over time," according to the study's abstract. 

As you can see, the blue dots representing songs in minor keys become more pronounced in recent years, while red dots representing happier sounding-major keys decrease. The dots also collect further down on the y-axis, representing slower tempos.

By going to the full interactive here, you can roll over individual dots to see what song each dot represents. For example, Jeremih's "Birthday Sex" in 2009 was both slow and in a minor key, making it sound sadder than "Good Lovin'" by The Rascals from 1966.

Heavy metal icon Alice Cooper told Studio360 that songs are sadder now because artists want to be more mysterious. But, you know, who can complain when gems like "Birthday Sex" are being created?

Go to the full interactive to explore more.

Screenshot from WNYC via Studio360.org