The Dahlia Medical Center has 30 labor rooms, 15 combination labor and delivery rooms, and 3 delivery rooms. All of these facilities operate around the clock. Time spent in labor rooms varies from hours to days, with an average of about a day. The average delivery requires about one hour in a delivery room. The average time in a combination labor-delivery room is about 24 hours.

During an exceptionally busy three-day period, 109 healthy babies were born at Dahlia Medical Center. Sixty babies were born in separate labor and delivery rooms, and 45 were born in combined labor and delivery rooms. Which of the facilities (labor rooms, combination labor and delivery rooms, or delivery rooms) had the greatest utilization rate?