Well, Shadow, I guess if you want to be really picky you could say that there is no evidence to back up the suggestion of a correlation. I doubt Cedars has done any peer reviewed research to investigate and prove that a population with a higher availability of Internet access per head is less likely to be experiencing growth in converts to the Jehovah's Witness faith. I also suspect that a similar graph would be produced if you looked at proportion of those with higher education certificate, those countries with more children in school before 6 years old, higher levels of literacy, levels of belief in God and the Bible in general v secular opionins or any other number of comparators.
That does not mean there is not a link and you don't need to have a statistics degree to see that growth is lowest in countries with the best access to education and information. It will be blindingly obvious to the GB that the cash rich western sheep are (a) not so cash rich anymore and (b) stagnating. The growth that there is in the west is in the foreign language population. Brothers in western lands are tiring and either becoming more hardcore or just drifting. I am not predicting the end of the org anytime soon but I don't think their old school tactics of slow change over time will continue to work for much longer.