Musicians are singing a lot more about sex and a lot less about love now than they did in the 1960s, found data artist Nickolay Lamm when he analyzed the lyrics of every song that has appeared on the Billboard Hot 100 singles chart since 1960.

“Money,” “weed,” “body,” “foul,” “hate” and “kill” also pop up more often now than they used to, while “lonely,” “sad,” “heart” and “I love you” were more popular in songs in the past, according to Lamm’s analysis.

Lamm created a series of charts based on his analysis, and they’re fascinating.

Here’s how to decipher the charts, according to Lamm.

The horizontal axis is the year of the song's release and the y-axis is the song's popularity according to Billboard Year-End Hot 100 singles. Each cell represents a song. The more red a song is, the more often that particular word appears in the song. For example, if a song has 5 "love" words and a total of 100 words in the entire song, that song is assigned a 5 percent value and a particular shade of red. The higher the percent, the darker the shade of red.

Take a look:

love
Love. Nickolay Lamm
sex
Sex. Nickolay Lamm
sexy
Sexy. Nickolay Lamm
body
Body. Nickolay Lamm
foul
Foul. Nickolay Lamm
hate kill
Hate or Kill. Nickolay Lamm
boys
Boys. Nickolay Lamm
girls
Girls. Nickolay Lamm
smile
Smile. Nickolay Lamm
i love you
I love you. Nickolay Lamm
we us
We or Us. Nickolay Lamm
money
Money. Nickolay Lamm
home
Home. Nickolay Lamm
weed
Weed. Nickolay Lamm
rain
Rain. Nickolay Lamm
kiss
Kiss. Nickolay Lamm
happy
Happy. Nickolay Lamm
baby
Baby. Nickolay Lamm
heart
Heart. Nickolay Lamm
lonely
Lonely. Nickolay Lamm
sad
Sad. Nickolay Lamm