Pl explain w/detail how CM ratings are calculated

I apologize if there is a thread with regards to this, but have looking for the past few days and have not found one. I also tried going through the CM itself and couldnt understand the maths behind the ratings calculations. A year or two ago when the CM rating was started, I do remember that it was explained in detail, but didn't register the information at that time.

Could someone explain it to me and could an explanation (small note) be made at the bottom of every week's CM rating to let members know how it is calculated - Seeing that so many members take the CM rating very seriously 😊

Regards

Shraddha