the commercial quota

I admit that I'm in a TV mood and not the the TV itself but mostly just lying here on the couch and dozing off with something in the background and at the same time I need to avoid Mitt Romney's acceptance speech, so I am zipping all over OnDemand and my recorded DVR stuff.  And, as I am watching The Big Bang Theory and fast-forwarding through the commercials, I am noticing once again what a large percentage of a half-hour show is made up of commercials! Didn't this stuff used to be regulated by the FCC?  Did Congress override?