What happened to the Elysium servers population?

Hello everyone, I recently returned after a few months off to the Elysium server where I used to raid on the alliance side and have found that my old guild (an Australian timezone raiding guild) had stopped raiding. I then saw that Anathema has peaked at 9k players since we became lights hope.

Did it simply haemorage population? And as an Aussie who would like to raid casually (which requires a very large population server to support) would it be best to reroll on Anathema, where there is an active Australian raiding guild?

Thank you very much for your time everyone, and have a wonderful day :)