bonsai
that's a recent addition.
I believe it is just the average score out of five.
Though, Sharky, that averaging you mention cannot be totally correct. Earlier when I had 8 out of 8 '5' scores, Skimbleshanks, in order to illustrate the idea reduced me to 4 out of 5 and I turned rainbow. She then changed me back to 5/5 and I went back to green.
Then also the ninth person to rate me could have given me only 1/5 but by the simple average calculation I should have stayed green but I didn't!
Not that I 'm complaining or anything, it doesn't really matter at the end of the day!