According to OMG Ubuntu!, the popularity of the GNU/Linux operating system rose to a total of 2.33% in July of this year, a notable increase from 2.02% in June. In August, that number dropped to 2.11%, rose up back to 2.23% in September, eventually leading to 2.18% in October. OMG Ubuntu! has gotten their statistics from web analytics company Net Market Share. (Full disclosure: OMG Ubuntu! only shows stats from July, and September. I got the stats from June, August, and October by visiting Net Market Share at the same URL posted on their page, and subsequently re-posted above).
However, as OMG Ubuntu! mentioned, verifying the accuracy of statistics like those of Net Market Share can be nearly impossible to do. Proving this point, they also reported statistics published by The WikiMedia Foundation, which show "a more familiar figure of ~1.2%" for GNU/Linux systems.
Personally, i suspect this surge may have had something to do with the end of the free Windows 10 upgrade offer. Perhaps people who wanted a new OS, but hadn't made Microsoft's deadline, have decided to look at alternative options. Or, perhaps they simply don't trust Windows 10 to run quickly, reliably, securely or any combination of the above. Or perhaps they don't like the idea of big brother watching them. There are also those who don't like Microsoft's latest GUI designs, especially the live tiles. These users might have been looking for an OS with a more traditional desktop environment.
in any case, it seems this rise in popularity might not last. The numbers declined somewhat since July, indicating that GNU/Linux systems might drop to below ~2% by the end of the year. On the other hand, the numbers between August, September, and October haven't fluctuated by a particularly large amount, so these numbers might remain steady. Only time will tell.