The growth of Islam pretty much can't be denied on any level. It is flat crushing Christianity. Now I don't know exactly what that means necessarily but those are the facts.
My only question would be why does Jehovah's spirit directed organization not enjoy the same growth. This is important due to how often the organization wields it as if to say see we're legit.
Apparently God likes Islam better than?
So this isn't about whether you believe in this faith or that, more about if touting growth as validity of backing then why is this happening?
As to the chart It is just a Trends chart. The thing about these things is they are for real in that MA types (mergers & acquisitions guys) use this sort of data religiously (pun intended) to detect whether there are growth possibilities in a given sector.
In various searches (the org post just on the main words "jehovah's witnesses") it is clear there is a decline among the masses when searching on this topic.
There just isn't the same interest as before. So searches like the above and "what do JW's believe" have all dropped off a bit.
However search terms/keywords related to JW's and child abuse have spiked.
The point to this exercises is that it isn't the end all be all but there is little doubt in my mind that the foothold has slipped due to the amount of information now reaching active witnesses, those studying or those interested.
Bottom line the Tower has buckets of money and they're streamlining. They have staying power from that respect but I can see a time where they're a shell of what they once were much like Scientology has become.
Just my .02 do what you will with it.