devs did not set the threshold,
it's the result of community commpetition to get on top 200 hourly list
by the look of it, threshold should drop even lower soon

anyway, I was off from solving captcha in the last 2-3 days
I started for about half hour (top) and my result was reaaaaally bad 
then I continue for another half hour (bottom) and ...whew... I managed to do better
I think that first half-hour is my worst record
if you were wondering, those stats are my js inject to monitor my claims