I took the survey, and am not all that interested in the Karma point... I just wanted to brag that I wasn't far off on the calibration. I gave a pretty low confidence level, however.

...though in thinking about it now, my confidence distribution is spread pretty far towards the earlier side of things. I would not have been surprised to find that my guess was half or an entire century later than it actually was, but I would have been extremely surprised if my guess was 30 years earlier than the actual date.

Maybe that's not too surprising, that I feel more confident estimating more recent historical events than those farther back.