Network Atlas - Bandwidth utilisation on Interfaces

Hi

Im trying to implement a map where i can monitor the % utlisation on my internet routers. I cannot use the built in feature on the new version of NPM 10.7 because the internet interfaces do not connect to any device which I monitor (which is normal as these devices' next hops are at my ISPs)

I managed to progress on this front by creating up and down arrow icons and placed them in my user graphics folder of network atlas and then assigned the same interface to an up and to a down arrow and adding labels ${InPercentUtil} to the down arrow and ${OutPercentUtil} to the up arrow.

However, the issue i'm geeting is that these arrows remain green all the time and are red only if the interface is down. I would have liked the arrows to change colour according to percentage utilisation like

<70% Green

70% - 90% Yellow

>90% Red

Is this possible? if yes how? I have attached a screen shot of my map

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Clik here to view.