On January 4, 1936, "Billboard" magazine published its first music hit parade. The first Music Popularity Chart was calculated in July 1940. A variety of song charts followed, which were eventually consolidated into the Hot 100 by mid-1958. The Hot 100 currently combines singles sales, radio airplay, digital downloads, and streaming activity (including data from YouTube and other video sites). All of the "Billboard" charts use this basic formula. Which stations and stores are used separates the charts; each musical genre has a core audience or retail group. Each genre's department at "Billboard" is headed up by a chart manager, who makes these determinations.