OK - I'm happy now, what is plotted is Mean Noise Density in dBFS/Hz which will result in the more typically quoted noise floor of ~ -94dB for a 16 bit converter.
Is there a post somewhere that explains the equipment used and signals levels etc. in generating these test results?
I'm a little confused that you're measuring noise floors down at -130 ... -140dB dBFS from a 16 bit system?