how would you measure that? by self reporting?
"I swear, I totally didn't spend 2 hours on youPr0n yesterday" :D
Once the data is loaded, no one can tell how long of your personal time you spend looking at whatever website. It has to be measured by volume of data being transfered
All that gets logged by the places you visit and other connection/session state tracking systems.
Massimus - "Trump already has democrat support."