if there are no negative ratings
score = 0
for each rating, oldest to newest
if this rater has already been counted
continue
score += min(10, round_up(months since rating))
else
score = unique_positive - 2^(unique_negative)
if score >= 0
start_time = time of first negative
score = unique_positive since start_time - unique_negative since start_time
if(score < 0)
return ??? (orange)

move score to range [-9999,9999]
return score