I don't know. Not even sure this is the lowest. It looks pretty bleak as far as activity though. I would love to see some data visualization detailing the downfall...
There was a low point just before the LW Survey came out and everyone got the mutual karma bump for posting "I did the survey" temporarily inflating contributor scores. But now all those +1s have fallen outside the 30 day window, and not even the open thread is attracting comments any longer.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Notes for future OT posters:
1. Please add the 'open_thread' tag.
2. Check if there is an active Open Thread before posting a new one. (Immediately before; refresh the list-of-threads page before posting.)
3. Open Threads should be posted in Discussion, and not Main.
4. Open Threads should start on Monday, and end on Sunday.