Currently the Percent-Page Viewed Plug-In is triggered on the next image request (second page, exit link). This methodology does not capture Percent Page Viewed data for single page visits where no exit link is clicked (majority of single page visits). This leaves a lot of guessing as to what visitors saw in their only pv and a large bucket of "undefined"
It would be great if that plug-in could be revised to capture single page visits (probably tricky but you guys are smart ;-) )