"Web usage", as a percentage, usually means "site visits", not "web users" or "devices". Most people do not own tablets, outside of pretty narrow demographics.

"Web usage", as a percentage, usually means "site visits", not "web users" or "devices". Most people do not own tablets, outside of pretty narrow demographics. Most people who have a smartphone do way less browsing on it, by number of site visits, than they do on their computer.