I don't know that exact ratio, but the number of stars that you can see that probably have planets in their "habitable zone" is pretty high... One in 5.

https://www.popsci.com/article/science/one-five-sun-stars-ha...

In our solar system, 2-3 of the 8-9 planets are in the "habitable zone". So let's just say it's maybe one in 20 or so.