I have a lot of planets that have an approval rate of 50 and. A huge number of it always comes from "population".
What does it mean? Say for example this: http://imgur.com/a/Ox527 What can I do to improve my approval?
There are several ways to improve your approval:
The reason your approval is low is due reason #2. 20 billion (and you are really close at 19.75b) is roughly the cutoff point for managing approval. Any more population and its not worth the extra effort to maintain approval.