Thanks for your answer @MortenCopenhagen
I am aware of the new metrics Google introduced in Maps, and they are quite helpful. My proposal suggests a different approach in the presentation of data that is already there. To be more clear, each review is already associated with a date, so, if for example I, as a user, want to see myself what reviews are more recent relatively to others, I can do it. If a place has many 1 
reviews the last months and an average of let’s say 4.2, that means the average used to be higher.