I should note that the above figures are based on AVERAGES. As you might expect, there were always countries that bucked the trend. For example, only 14.5% of Cuba's population have access to the internet, but they still only managed a 1% increase in publishers. At the other end of the scale, 58.8% of Malaysia's population have access to the internet, but the Society still managed an 8% increase in that country. However, such exceptions are rare, and the overall trend (as shown above) is that "ignorance is bliss" - at least as far as the preaching work is concerned.
Something else to take into consideration regarding countries that buck the system is the percentage of elderly population. Even if there is reasonable internet access in a certain country that also has significant growth for the Watchtower, how much of that particular population is willing or able to use a computer? My non-jw dad is 73 years old and lives in the US. He has a computer and internet service but absolutely refuses to use it. At least in my neck of the woods, I've found that many people who are in their 70's or older are petrified of even trying to use the internet.
On the other hand, in countries where internet availability as well as Watchtower growth is low, is there a significant portion of the populaion that is young? Although younger people may not have immediate internet access, they may be more willing and able to use a computer at a library, school, work, or friend's home than their senior counterparts.
Just a thought, but it does seem that you're on to something.