References to sex in songs have grown dramatically in recent times, suggests a new analysis of popular song lyrics in the US from 1960 to 2008.

Among female performers, the proportion of songs referring to sex was at 6% in the 1960s, then jumped to 16-21% from 1970-2000.

Among male performers, the proportion of songs with reference to sex jumped from 7% in the 1960s to 20-29% through the ’70s, ’80s, and ’90s, then jumped to 40% in the 2000s, the findings showed.

“References to romantic relationships became less common over time, while references to sexual behaviour and objectified bodies became more common,” said the study, published online in the journal Sexuality & Culture.

The analysis relied on the Billboard year-end top 100 songs of the year for 1960 to 2008.

The top 50 songs from every even numbered year were analysed, providing a sample of 250 songs per decade and a total of 1,250 songs.

The study conducted by Jennifer Shewmaker from Abilene Christian University in the US and her colleagues also found that men sing about both romantic love and sex more often than women. However, female artistes sing about romantic love in a higher percentage of their songs.

The difference is due to gender disparity in the number of songs. Male singers performed a considerably higher percentage of popular songs than female performers during the study period.

A total of 895 unique primary artists performed these 1,250 songs. More than half of songs in the analysis were from the rock/pop genre, although its dominance decreased over time, particularly after 1990, the study showed.