On this Valentine’s Day, let’s look at an article that analyzes the 100 most popular songs between 1958 and 1998 for performer demographics and expressions of love.
In the 1990s women and black artists recorded more hits than in earlier periods; over time, references to love in lyrics performed by women artists decreased. References to sex in lyrics peaked between 1976 and 1984, when women used sexual references five times more than men; however, between 1991 and 1998, men used more sexual references.
Later songs and songs performed by white female artists expressed greater selfishness; the quality of love expressed in the lyrics remained the same.
This according to “Expressions of love, sex, and hurt in popular songs: A content analysis of all-time greatest hits” by Richard L. Dukes, et al. (Social science journal XL/4  pp. 643–650). Below, the Beatles—with a little help from their friends—provide further analysis.
Related article: Sexual attraction by genre