I think it depend on how many broadcast at the same time, and how many people are watching?
Let say example, there's 10 different broadcasts starting at 7pm.
The total of people watching are100.
If all 100 is watching same broadcast, that broadcast got 100% rating, while the other 9 broadcasts got 0% rating.
But there's no way everyone gonna watch the same thing that's how the % divided.
....
But say, a household of 5 only have 1 TV to watch, then they are counted as 1.
So 5% is not bad, the drama can wrap up as it initially intended.
But if the rating drop to 2% or below, drama will be cut short or worse, stopped without any ending and be replaced with other drama.
I can never understand the small percentages of TV ratings and shares of a company because apparently even 5% is a big thing