How is calculated the "Memory Overall Workload" metric?

Hello,

My question may seem stupid, but I ask it because I'm in front of the following case:

I have an host in my vCenter that I monitor with vCops and the vSphere Client, and a few hours ago, I have seen an alert from vSphere telling that my host memory usage was high. And when I watched, in fact, 9.5GB of 10GB where used.

BUT... A few second after, I have seen on my vCops web interface that the "Memory Overall Workload (%)" was about 36%, whereas the "Memory usage" (still on vCops) was about 9,6 GB.

Consequently, I think that "Memory Overall Workload" is not equal to "Memory Usage" / "Total Memory Capacity" * 100

So, how is it calculated? What this metric really represents?

Thank you in advance,

Nicolas