A map for us to use on our trip to London!

The Billboard Hot 100 chart captures each week’s most popular songs across all genres. Rankings are determined by radio airplay audience impressions, which are measured by Nielsen Music’s radio SoundScan tracking program, Nielsen Music’s sales data, and streaming activity data from various online music sources. A common argument in music discussion circles is that modern pop music is worse than the music of previous decades due to its lack of variety; while this claim is difficult if not impossible to assess, the number of unique songs and artists reaching #1 on the Hot 100 chart provides a proxy for evaluating the relative diversity of popular music over time.