The number of commercial breaks in one episode

[Nico Darko]

Hi.
As someone fascinated by television writing, I often pay attention to how many commercial breaks (and how many acts) an episode has.
The big networks used to have 4 breaks in one episode (usually a teaser followed by 4 acts), but they started to switch to 5 breaks around 2004, and it is now the norm for network and basic cable shows. I find it interesting because it had a significant impact on the writing (more scenes or more mini cliffhangers, and a faster pace). To my knowledge, a very small number of channels still has 4 breaks (CBS, AMC, FX... correct me if I'm mistaken).

My question is: is there a list of somewhere that indicates how many commercial breaks there are (by tv shows or by channels)? And where can I see the evolution over the years?
I did find a few shooting scripts of some shows, where you can see how many acts they have, but I'd love to have a real overview.

Thank you.