The network hashrate at 10/1/2017 was roughly 8EH. Today it is almost 16EH.

How is that possible? Does it imply that in 3.5 months the number of miners doubled? Did the world manufacture that many mining machines in the months leading into the past 3 months? Mind you that in Oct, 8EH was an all time high, so its not people pointing machines back at BTC. How can you double in 3.5 months?

Is there something flawed in my assumptions? Is EH not a proxy for # of mining machines?