What are you basing that notion on? We know for sure of the existence of (semi) intelligent life on 1 planet out of 9 in our solar system. If it's only that one planet, we don't know. So we've been on Mars and taken pictures of the other planets... how many species are there on our own planet that live miles underground and survive with no oxygen and no light? We've found a couple, and there may be many more than that. Just because we can't see them doesn't mean they aren't there. And again, we can present only a lousy probability because we don't really know anything about any of the other planets. We know that at the bare minimum, one planet in our solar system contains life. What if we find life on Titan? Suddenly we have the evolution of life on two different planets within one solar system, one of which we consider intelligent. How many solar systems in our galaxy, how many galaxies in the universe? And you're going to say that even given the 11% minimum chance that Earth had in our solar system, there's a one in a billion chance of any galaxy having intelligent life? We don't even know if we really are the most intelligent species on this planet. Whales and dolphins seem pretty smart. Who knows what else is hiding here?

The point is, nobody on this planet is in absolutely any position to say how many (or few) planets have evolved intelligent life. We know damn near nothing about anything regarding the universe.