I've been stuck at 99.9 all frickin day, but I thought I'd post a mini-guide on exploring the only non-straightforward zone, that being Tihark Orchard mission. You have to do it in the actual mission, since there is no explorable zone.
1. Set up with a build to solo a lvl 20 blood necro and a couple running skills, enter mission.
2. Dance with the little girl, re-enact the fight, and kill the lady with the rare artifact (do the other 2 mini-games if you're going for bonus), and go talk to the princes.
3. After the cutscene, all the guards blocking the stairs will have left their posts to attack the skree. Now's your chance to simply run outside and explore the whole zone.
It turned out to be about 1.5% I believe.
Edit: I got it.

Assembling the map now.