December 15, 2016. Difficulty rose by +8.16% to 310.15B from 286.77B.
Change
+8.16%
New difficulty
310.15B
Period length
12.9 days
Network hashrate then (7-day)
2.2 EH/s
Bitcoin price then
$777
Hashprice then
$670/PH/day
The 2,016 blocks before it took 12.9 days instead of 14, so the network had more hashrate than the difficulty assumed, and difficulty rose by 8.16%: a large adjustment. For every machine on the network that is a pay cut of the same size until the next retarget.