Does Every Galaxy Have a Black Hole at Its Center?

We can see trillions of galaxies out there in space. Can we tell what percentage of them have black holes? Or does every galaxy we've seen have a black hole in it that we can tell? Yeah, that's a great point. It's basically our strategy in physics. It's like look out of the universe, find patterns, wonder if those patterns reflect like deep rules of the universe,. figure out what those rules have to be.