Popular music has changed over the years, and the music of 2019 is noticeably different from the music of the 1960s or 1970s. But it is not just the music that changed, but also the lyrics. Data scientists at Lawrence Technological University in Michigan used quantitative analytics to study the change in lyrics of popular music over seven decades, from the 1950s to 2016. The results showed that the expression of anger and sadness in popular music has increased gradually over time, while the expression of joy has declined.