Billboard determines its top 100 singles of the year by analyzing a combination of album and song sales, radio play, and online streaming plays. The formula for calculating a song’s popularity rests on a ratio of about 35 to 45 percent sales, 30 to 40 percent radio airplay and 20 to 30 percent streaming plays. The end-of-year charts rank the most popular overall singles from the year based on this data.
Billboard uses data from Nielsen SoundScan to calculate album and song sales. This information service tracks both the physical and online sales of albums and singles at music retailers nationwide. Historically, SoundScan tracked physical album sales, but it now tracks digital sales from retailers such as Amazon.com and iTunes as well. SoundScan also catalogs sales from less conventional sources such as album sales at live concerts.
Radio airplay is another major component to determine Billboard’s top singles of the year. Billboard makes use of Nielsen’s Broadcast Data Systems service, which tracks airplay on stations nationwide. The service uses pattern recognition technology to identify which songs are being played 24 hours per day.
Streaming plays from services such as YouTube have increasingly become a part of Billboard’s formula for chart success. Although streaming plays count proportionately less than other metrics, many newer songs by younger artists receive major boosts from streaming, such as Miley Cyrus’s 2013 hit “Wrecking Ball.”