Math weirdness

I've been using Runewise for a couple of years and I'm finally going to ask about the relationship between goal percentage completed and exp remaining.

Using the picture above as a reference, can someone explain to me why mining, which has the most exp left to gain, has the highest completion percentage?

Two more things

While working on the elusive 5-feathered flappy hats, I noticed my avatar's AI is still awful when I'm trying to target chompys. I'd say perhaps it's due to lack of line-of-sight between me and the chompy, but this whacko delay between my clicking on one of the birds and when I actually get off my ass to fire my stabby chucker (about 3 seconds) can happen when I'm standing right next to a bird or refilling my bellows behind a small hillock with my back turned. 

The other thing has to do with Jagex's magical math-fu. Can you see the mistake in the following picture?