Every Billboard Hot 100 song since 1958:

The 857 songs used to make the piece are analyzed digitally and a spectral average is then derived from the entire song... The spectral average of each song used in Billboard plays for one second for each week it stayed at #1 on the Billboard Hot 100. Thus we run about 52 seconds per year, for a grand total of a 37 minute sound work.

Link: Billboard
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