SELECT T2.name ,  avg(T1.stars) FROM Rating AS T1 JOIN Reviewer AS T2 ON T1.rID  =  T2.rID GROUP BY T2.name
What is the average rating star for each reviewer?
[Schema (values) (types)]: | movie_1 |  Movie : mid (text) , title (number) , year (text) , director (number) | Reviewer : rid (text) , name (number) | Rating : rid (text) , mid (number) , stars (text) , ratingdate (number);