A large black patch surrounded by a large white area. Used a Minolta Spotmeter F. Made several measurements which were quite consistent.
I think he Spotmeter F measures peak intensity, but I think the results are quite valid in this case.
I repeated the measurements in a dark room, I got 1.8 -- 8.2 EV : 1:83 or 6.4 stops.
I also measured with a very old Minolta Autometer II and got 2.5 -- 8.5 EV, or 1:64 or 6 stops.
I could also mention that I have analyzed quite a lot of raw images using RawDigger and found a single image having a DR more then 9 stops, and that was a dupe I made from a Velvia slide, after shielding out all light leaks. Most images fit comfortably in a 9 stop range and that is mostly due to lens flare. Yes, I can get a DR of 12 stops on a Stouffer wedge but it is no easy.
Did you measure two different screens, one all white and one all black? That will tell you what more or less what the monitor will do with no one in front of it. If you have two equal patches, one black and one white, on the screen at the same time, that's closer to a realistic test. Taking a typical image and embedding a black and a white square is probably the most realistic, especially if you sit with he meter in your hand where you'd be if you were actually editing.