December 18, 2018. Difficulty fell by -9.56% to 5.11T from 5.65T.
Change
-9.56%
New difficulty
5.11T
Period length
15.5 days
Network hashrate then (7-day)
38.0 EH/s
Bitcoin price then
$3,557
Hashprice then
$167/PH/day
The 2,016 blocks before it took 15.5 days, longer than the 14 intended, so hashrate had fallen, and difficulty fell by 9.56%: a large adjustment. For every machine on the network that is a pay rise of the same size until the next retarget.