I don’t think there is an open database for historical development of the estimated network size. This topic serves to become one, even if in a very crude form. You can help by screenshotting the numbers from https://autonomi.com/ whenever you feel like it, and marking the UTC time of it.
Disclaimer: I think the past 3 months are more accurate than the months before due to certain code changes in antnode itself.
Estimates prior to 04-2025 were definitely off for few reasons (mentioned in antnode changelogs etc), for which code changes were made quickly to address the issue.
Internally, we are continuing to track metrics on production infrastructure since 12-2024.
There were some drops in network size (large percentage) (dip and bounce back etc), I won’t go into that as it may have been covered by weekly updates, but internally, we did observe them, and held discussions around those events. However, here is a chart with a moving average (60) applied for past 6 months:
Additional Note: As and when we release a new version and our nodes are upgraded, there is a drop in the metric, but that quickly heals and becomes more accurate within 24 to 72 hours.