By last report, 17% of TV shows, 13% of the population.
Clearly you didn't discern this from watching TV. You just kinda sorta feel it's true.
And this is a rebound from decades of your generation and the prior generation shutting them out. So find a mirror and complain to it, or give yourself credit. Whatever suits your mood.
TV commercials are a different matter. There are far more than 17%.