On the average Web page, users have time to read at most 28% of the words during an average visit; 20% is more likely.This inspired me to look more closely at webstats. Unfortunately, Google Analytics only provide average time on each page so it only takes one person to leave a page open while they go and make a cup of coffee and the data becomes pretty meaningless.
However, my click analysis tool Crazy Egg provides a modal breakdown of time to click (and therefore time on page). So I can see x% clicked after 2 seconds, y% after 5 seconds and so on.
My focus has been on homepages - particularly school homepages full of text - and sure enough, most people read next to nothing.
How Little Do Users Read? - article by Jakob Nielsen
Crazy Egg click analysis tool