THS7530: CMRR curve, data sheet figure 12

I don't understand the sign of the CMRR curve in figure 12 of the data sheet.    I believe that the CMRR definition is the ratio of common mode voltage applied to both inputs to generate a given output voltage A,  divided by  the differential input voltage applied to generate the same voltage A.  Hence I would expect the ratio to be > 1 and thus positive dB values since the common mode gain should be less than the differential mode gain.   Figure 12 suggests the common mode gain is greater than the differential gain, implying that it takes less common mode signal to get output A than the applied differential signal.  I would be happy if you just told me the sign is wrong. Then I would see large values of CMRR at low freqs which is what I would expect.     What makes this even more confusing is the dc common mode rejection ratio is +114 dB at room temp and the power supply PSRR is +70 dB.  Am I missing something?  I am not an expert on this so I apologize if this is a silly question.