Attenuation percentage within a segment

I am quite new at 3D Slicer. I have done some muscle segmentations (HU between -29 to 150) and I would like to further classify the percentage of the segmented area according to a range of attenuation.

Example: 20% between -29 and +50
80% between +50 and +150

I have tried to use LungCTAnalyzer unsuccessfully for this. Is the some extension for this?

Regards

Anyone that can help?

Here is a python script example which would allow you to gather all the voxel values within a given segment into a numpy array, where you could perform whatever binning you would like for further analysis: Get Histogram of Segmented Region

Thank you @mikebind !