I think there is a for real bug/screw-up in the interface. If you look at the end, your "extra planet" is a total of all your points from each category, and you can obviously not get a negative score anywhere, you just get a lower positive one. My total was 100%, not 200%. Why the extra planet? It's a mistake.
If you subtract one from the result, the lowest possible score is actually 0.23, not 1.23.
