Faction, dread, and titan rats

So lately I’ve been on a pirate dread hunting kick. I love finding dread rats or otherwise rare rats. I’m hoping to stumble upon a titan rat or an officer.

I did a lot of research but the problem is the stuff I found online was several years old.

What I’ve been doing it going from belt to belt in systems with a lot of asteroid belts, and killing the rat spawns over and over. Every once in a while I get something good.

But does anyone have insight into the random percentage for these rare rat spawns?

Like 1 in 50 is a dread (as example). Any info would be appreciated!!!