I was talking about upstream bandwidth growth, not total bandwidth growth. Unfortunately, upstream bandwidth growth seems to be much slower than downstream growth.

In the document I linked (from 2011) downstream bandwidth growth was about 50% a year - your documents and Nielsen's Law confirm this trend is, approximately, continuing until today. But upstream growth was then expected at 10% annually, with a slow increase in the last years covered - so I was estimating 10 to 20%. As I was told by small-block supporters, upstream bandwidth is equally important than downstream for the Bitcoin network to work well and so it is the real bottleneck for the Bitcoin block size.