The graph makes sense if you keep in mind that the electrogravity field is proportional to the speed of the rotating charge and so the largest effect is naturally along the edges which has the largest speed. Interestingly, the graph does show an increased field-strength along the edges of the disk, which also means that this is where the field divergence will be the strongest. If you did your homework and now understand the basic electrogravity axioms, you will also understand why an object placed above the center of the disk will experience a sideways pull toward the more dense field region at the disk edges. It is not known if the charges on the disk are mainly positive or negative, but there is a possibility of a positive ion buildup in the rotating superconductor, which would produce a reverse electrogravity field, that tends to un-polarize the atoms in a test object above the disk with a resulting weight-loss.
Another puzzle which has caused some people to wonder whether it is some sort of gravity shielding, or is it a antigravity generation? This question may now have been answered, as a new paper by Dr. Podkletnov (see reference) uses a disk with a large hole in the middle. The maximum weight-loss is still 2% under this configuration! Is anyone still claiming that a rotating disk with a large hole in the middle is a gravity shielding device?
If you have read the white paper on the electric field with similar properties to that of gravity, you will remember that all rotating charges generate an electrogravity field, see these axioms for a summary - which explains the Tampere device as generation of electrogravity - not a gravity shielding device.
Most sane scientists agree that gravity fields are not shieldable. However, by understanding the electrogravity theory - the electrogravity fields can be canceled by opposite polarity electrostatic or pure electrogravity fields, as described here.