MSNBC has a post referencing a study that shows the internet access for Tablets.
Wi-Fi beats cellular for tablet connections
Myself all my tablet type of devices are wifi only as I connect them to my Verizon 4G wifi device. If you look at the cost of cellular coverage for a tablet it is daunting for many.
Take the iPad, for example; AT&T's plan for it is $14.99 for 250 MB of data a month, or $25 a month for 2 GB of data. Verizon Wireless charges $30 for 2 GB a month, $50 for 5 GB; and $80 for 10 GB. To boot, a Wi-Fi-only iPad, with 16 GB, costs $499, compared to $629 for a model that also has a cellular chip in it. The same is true for other tablets that come in both Wi-Fi and Wi-Fi/cellular combinations; there's a premium to be paid for having both.
Honestly, my shared connection device is often less than 1GB a month, but can change when I travel more.
Data above gives you some ideas of what the general population dose. But, I am amazed there is a percentage of people with None of connectivity. I wonder how they use their devices?