Series Premiere Ratings
Wikipedia, which is famously unreliable, says: "the show's first episode had the highest ratings in recorded television history." (At least, it says this as of December 10th, 2009. It could change at any time, of course.)
What the heck could this mean? Clearly, the 'Mayberry R.F.D.' premiere didn't have the highest ratings of any show that's ever aired. Maybe it's the highest-rated spinoff premiere?