December 6, 2015. Difficulty rose by +8.77% to 79.10B from 72.72B.
Change
+8.77%
New difficulty
79.10B
Period length
12.9 days
Network hashrate then (7-day)
0.6 EH/s
Bitcoin price then
$387
Hashprice then
$2,344/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 8.77%: a large adjustment. For every machine on the network that is a pay cut of the same size until the next retarget.