It's not as simple as just looking at what witnesses are powering down though. Some power down only a fraction of their rewards to cover server costs, others power down to distribute it to a team of people that run a witness together.

For almost 2 years of running a witness and having a delegation, our steempress account was powering down, but I was powering up 100% of all rewards from early 2018 to early 2020, not selling a single token since Jan 2018. But if someone just looked at the witness list, they would think that we were powering down, while in fact, I was the only person receiving a steemit delegation who powered up 100% between 2018 and 2020.