I wonder what is classed as "internet usage". In the broadest sense you could say I never stop using the internet as my phone is always connected to it and always exchanging data. Beyond that you could differentiate between spotify use of streamed and already downloaded songs as an example. Or does using my kindle (which is connected to the internet, yet I am reading an already downloaded book but constantly synchronising my progress / looking up words) count or not count? What about playing COD? It demands an internet connection even in single player but is offline but online. And don't get me started about smart TVs....
It gets very complicated. Almost as complicated as the question "how many computers do you have in your house?"