I used my lead kebab test rig with this extruder, which has a 0.5mm nozzle: -
Most measurements are averaged over 8 tests of extruding 40mm of filament, so it took a long time to get these results.
These are the basic measurements: -

Flow rate for a given force seems to increase fairly linearly with temperature. The single points are the weight that I found gave about my normal extrusion rate of π mm3/s. Below are the same points plotted against weight: -

So force does increase rapidly below 220°C.