591
Stack Overflow in freefall: 78 percent drop in number of questions
(www.techzine.eu)
This is a most excellent place for technology news and articles.
When it was just SO I think... if my memory serves. When it was small enough that only a (relative) few programmers were using it and generally behaving well.
It's 17 years old, so probably only in the first 2 or 3 years. 2010 is when it got VC funding and is probably when it started to got to crap.