Broad Ratings Shifts

Many movies have seemingly simultaneously changed in rating recently. Why is this?

Notably, during the last week (at most) the first two films of The Dark Knight trilogy went up by 0.1 each; the entire Sam Raimi Spider-man trilogy went up by 0.1 each; The Avengers and Avengers: Infinity War also went up by 0.1; Interstellar did the same; the entire The Lord of the Rings trilogy; The Hobbit: An Unexpected Journey; the Back to the Future trilogy, Jurassic Park, etc... all in the past couple of days. How is this possible?