Help in research (very simple task for professionals)

I'm doing my master degree research on simulating particles using Discrete Element Method. I'm simulating 1000 particles and each particle have its own rotation matrix (9x9) or quaternion (1x4). I have all the data in excel sheet attached below. The job required is to get an average rotation matrix or average quaternion for the all 1000 particles providing me with the steps and references.