This is an extraordinary news for us! For almost 10 years I was hoping to see that and, finally, I've seen it!
In short, it seems that we reached the bottom in participation in 2014 and that we are now slowly going upwards.
My claim is based on the analysis [1] of the Eric Zachte's participation statistics on English Wikipedia [2], but I am almost sure that the rest of the projects more or less mirror it. But, anyway, I encourage others to check other projects and other relevant factors and see if their results correlate with what I have found. The reasons for the change in trends should be also detected.
If we are looking Eric's statistics from 2010 onwards, it is not immediately obvious if we are going up or down. We reached the peak in 2007 (German Wikipedia somewhat earlier, other projects later, but English Wikipedia is approximately 50% of our activity and its weight is too strong for other projects to balance our overall activity). After that peak, we went down as quickly as we reached the peak. Then, in 2010, the trends flattened.
However, it was not a stagnation, but barely visible recession. However, that "barely visible recession" removed approximately 20% of the very active editors in the period from 2010 to 2014, while the "visible one" -- from 2007 to 2010 -- was also approximately 20%. At that point of time, in 2014, the next 10 years would for sure drive Wikipedia and Wikimedia movement into insignificance.
Comparing such data is also tricky. It's not just necessary to compare the same months (January 2010 with January 2011, 2012 etc.), but there could be "freak" months, which are not following general trends.
That's why I used two methods: One is coloring the months by place in comparison to the months of the previous years. The other is average number per year.
There are at least a couple of important conclusions:
1) Negative trends have been reversed.
2) Both 2015 and 2016 were not just better than 2013 and 2014, but even better than 2012, while 2016 is just a little bit worse than 2011!
3) December 2016 was even better than December 2010!
4) I could guess that the period June-November 2016 was worse than the same period in 2015 because of the political turbulence. Without them -- as May and December 2016 likely show -- 2016 would be not just better, but much better than 2015 and maybe even better than 2010.
I would say that the reversal is still fragile and that we should do whatever we've been doing the last two years. Yes, detecting what we've been doing good (or bad) is not that easy to detect. But, yes, better analysis of all of all of the processes should be definitely done.
I hope that this shows that we are at the beginning of our Renaissance, Wikimedia Renaissance and that the Dark Wikimedia Age is behind us! So, please join me in enjoying that fact, even I could be wrong. It definitely sounds definitely amazing, even it could be just my imagination! :)
[1] https://docs.google.com/spreadsheets/d/1IXYoTI_nCBhhuJAknH5KL450_D3V67KWTHuo... [2] https://stats.wikimedia.org/EN/ChartsWikipediaEN.htm