The vast majority of all sitcoms, dramas, news, and nearly all movies are filmed at 24fps.
While the material may have been filmed at 24fps, it was never broadcast at that frame rate. NTSC broadcasting as well as digital broadcasting use a frame rate of 29.97fps (rounded up to 30). 24fps source material is converted to 30fps using a process called 3:2 pulldown. Current broadcasting is done at 30fps, which is exactly why televisions offer refresh rates like 120 Hz or 240 Hz, which are multiples of 30. Notice they don't offer refresh rates of 96 Hz or 192 Hz (which would be multiples of 24).
The reason this looks bad, especially during pans, is because the older NTSC broadcasts didn't actually use 30fps, they really used 60 interlaced alternating-line frames per second. This was because the tubes couldn't draw the full screen in 1/30th of a second. When video and broadcasting went digital and screens could be drawn fast enough, displays were able to produce 720p and 1080p, which is progressive, meaning the entire screen is drawn in one pass from top to bottom in 1/30th of a second. During a pan, the objects on the screen have moved horizontally during the 1/30th of a second it takes to redraw that part of the display. This can make it look jumpy and/or pixelated. The higher refresh rates attempt to deal with this by redrawing the screen faster, or inserting interpolated frames so there isn't as much perceived object movement between screen redraws.
The only place you are ever going to find true 24fps material is from a DVD or Blu-Ray disc. The material on the disc can be encoded at 24fps and either output at 24fps if the display can handle it, or the player can perform the 3:2 pulldown and convert it to 30fps, if that is all the display can accept.