Right, here's another animated GIF with the paths of all salary bands marked in. Click on it to animate it. It looks like blogger will only allow one animated GIF per post. (Finally - only took six attempts to get that to work properly!)
Notice how the trajectory of the lower salary bands is almost straight up - that is, the number of staff in those bands went up, but their salaries didn't. The trajectory for the upper bands is much flatter - the salaries in those bands shot up over the 4 years.
I want to see if I can do this with the Department of Climate Change next - assuming I can extract enough publicly available data from their web site.
By the way, I stole the idea for this data visualisation from a great TED talk by Hans Gosling. Suggest you check it out.