CBS Radio Mystery Theater is a radio drama series created by Himan Brown that was broadcast on CBS Radio Network affiliates from 1974 to 1982, and later in the early 2000s was repeated by the NPR satellite feed. Wikipedia
CBSRMT was broadcast each weeknight, at first with a new program each night. Later in the run three or four episodes were new originals each week, and the remainder repeats. There were 1,399 original episodes. The total number of broadcasts, including repeats, was 2,969. Each episode was allotted a full hour of airtime, but after commercials and newscasts, episodes typically ran for around 45 minutes.