Hi Lawrence,
Thank you for your message.
Unfortunately this is not possible because the ratings are stored in CMS_Document table in columns DocumentRatingValue and DocumentRatings. The rating is calculated with DocumentRatingValue/DocumentRatings. In order to make what you need there is a requirement to store each and individual rating value to another table where the User, Document and rating value would be bounded.
Let me know if you have further questions.
Kind regards,
Richard Sustek