Wikipedia has a big chart which shows the fastest lap times for the various versions of the track, and the highest total distance covered for each version of the track.
I think it's interesting that the fastest qualifying time is held by the 917(not surprising, considering the speed of the car, and the lack of chicanes on the Mulsanne), and the only car to more-or-less equal the 917's race speed was the XJR-9, which came 17 years later.
Most of the post chicane-era had fastest qualifying laps in the 3:30 range(the first six years were slightly faster, but that was the end of the Group C era, correct?). Why then were the lap times in 2008 and 2010 so much faster than 1997-2007[10-12 seconds faster on fastest laps]? Was it a change in the track, or the cars?