No, I don't think so. Look at a bigger time frame:
https://metrics.torproject.org/users.html?graph=userstats-re...
There was a huge spike in Mid 2013, cause by a botnet that installed tor. Before there was almost not oscillation. After that there is quite a bit. I think there are many infected PCs at companies.
Do you still got a reference to news/blogs about that botnet install?
There is something form the official tor blog. https://blog.torproject.org/blog/how-to-handle-millions-new-...
¹ https://metrics.torproject.org/users.html?graph=userstats-re...