The hospital does account for ~33% of revenues[0], but the Med School and the Hospital also account for ~55% of total expenses[1] so it doesn't seem entirely unfair to include them in the revenue stream.

0: https://ucla.app.box.com/v/acct-pdf-AFR-15-16 page 37

1: https://ucla.app.box.com/v/acct-pdf-AFR-15-16 page 28