equally change the way of rating/percentage
I have notice that if someone leave a negative review the percentage goes down up to 4 points, but if someone leave a positive review it might go up one point if that, because sometimes percentage doesn't even increase. Therefore I suggest that it should be equally rated and it should increases or decreases equally whether is a negative review or a positive review.
We maintain the history of the community to show its evolution. However, you may appreciate a new rating summary we are launching in Q1 2020 which looks back at the last 12 months. We call it the epIQ grade. epIQ stands for experience and performance IQ.