Absolute graph with percentages

I have successfully created a graph that shows % disk usage via node exporter:

1-(node_filesystem_free_bytes/node_filesystem_size_bytes)

This works great, but I’d also be interested in the actual value, ie the numerator in the formula above. Actually, the preference would be something like “50GB (24%)” in the values.

Is this possible? I suppose generally I’m asking if one can annotate the displayed values, perhaps by passing a matrix instead of a vector to the graph (these are layman terms as I’ve just begun with Grafana).