January 23, 2013. Difficulty fell by -8.64% to 2.97M from 3.25M.
Change
-8.64%
New difficulty
2.97M
Period length
15.3 days
Network hashrate then (7-day)
—
Bitcoin price then
$18
Hashprice then
—
The 2,016 blocks before it took 15.3 days, longer than the 14 intended, so hashrate had fallen, and difficulty fell by 8.64%: a large adjustment. For every machine on the network that is a pay rise of the same size until the next retarget.