I believe thinking animals in human terms is wrong. It's one of the flags of the anti hunting party, also.
There aren't "stupid" species, as every single species developed a unique own way to adapt, survive, prevail, in a given kind of enviroinment. Obviously no other species than humans can write a book, compose an opera, built tools that are useful for building tools and so on. And that, by a specific human point of view, make our specie a milion times above all other ones. But, every other species is actually at the very top of theyr own evolution (for now), exactly like us.
We are not able to fly by ourselves, or reach the depths of the oceans, or do one of the many, infinite things that other species are able of. Maybe we could be considered "stupid" by a seagull or a whale.
I voted for 20%, but I believe, by human standards, they are far, far less intelligent. By evolution standards, 100%. Exactly like any other single species on Earth, fruit of milions of year of evolution.