I'm guessing 2012 because I
thought that was the year they stopped doing brain teaser interviews, which were very controversial at the time. Googling it now, the exact year is fuzzy -- like, they
originally stopped in 2006, but only fully stopped around... 2011-2012? My evidence is this thread and its linked article:
https://www.reddit.com/r/programming/comments/1gq72n/comment...