I need to get an idea of the average "time on page" or "page view duration" for each page on my websites without client-side scripting (such as using onunload event handler).

Is any of the free log analyzers capable of doing this? I looked at Webalizer, AWStats and Analog, but they don't seem to have such a function. The closest thing is "visits duration" in AWStats, but I'd like to see "page view duration" instead.

I know that visitor tracking is inaccurate without client-side scripting, but I can bear with it. Google Analytics seems to provide a "time on page" metric without hooking the onunload event (but correct me if I'm wrong), so I believe this is possible.