F10 520D efficent dynamics

Hi all I would like to ask something maybe someone knows? On my 520D on the consumption meter on the display when I picked the car up it had a efficent dynamic scale on the left side when I took my foot of the pedal it lit up the blue scale on the ffficent dynamics scale , I noticed this morning. The efficent dynamics scale has moved to the right hand side of the consumtion display it has changed position
What does this mean ?
Cheers