I've been watching the global estimated hash-rate, as estimated by blockchain.info.
While it is clearly increasing, it also varies around 20% day-to-day.
Yesterday, it was around 4,325,000 TH/s.
Today, it is 5,688,000 TH/s.
Wouldn't miners want to keep their equipment running 24/7?
That is a lot of hashing-power to go on and offline so frequently. What is causing this?