In 1935, they began publishing the earliest weekly music chart, preceding the Billboard singles chart, which was updated weekly by the Billboard magazine beginning on July 27, 1940.
The Your Hit Parade chart was established in April 1935, which operated under a proprietary formula to determine the popularity of a song based on five factors, including 1) record sales (divided between a) retail and b) wholesale), 2) sheet-music copies of the song (both retail and wholesale), 3) number of radio plays, a category that is sub-divided between a) plays on the three national networks and b) plays on local stations, 4) plays on jukeboxes, and 5) numbers of requests to orchestra leaders to play a particular song.
[1] As such, though the musicians who popularized each song are credited with having done so, this is not exactly the same as them having made a hit record.
A number of artists had number-one singles on their own as well as part of a collaboration.
† Includes two number-one hits co-leading the Dorsey Brothers The following artists were featured at the top of the chart for the highest total number of weeks during 1935–1940.