I bet you didn't take into consideration Pokemon abilities, tho. That will throw a lot of these numbers off, especally things like Levitate, Water Absorb, Thick Fat, etc.
I would not expect Ice to be on top. It is true that there are a lot of dragon Pokemon that are 4x weak to ice, but there are way more water Pokemon out there that will be strong to ice, or 4x strong to Ice. I find that hard to believe.