Bluebulb Projects' The Measure of Things presents:
9,100 is about one-fourth the number of Seats in Fenway Park.
In other words, it's 0.245470 times the count of Seats in Fenway Park, and the count of Seats in Fenway Park is 4.0738 times that amount.
(2013 figures; daytime capacity) (a.k.a. The Cathedral of Boston) (Boston, Massachusetts)