Nice and informative, but i do have one quibble. In your scale, green straddles negative and positive values. You should break it into 2 ranges, namely the negative one up to but not including zero, and zero to the positive value. I presume what you show is due to some natural breaks in the data. But it should also be about what the data mean.

Also a time lapse movie going back as many months as you can gather would be nice. :-P