During the month of May, there were 1500 patients admitted to the Hospitalist service (this is essentially a catch-all service). Of these, there was a total of 10 cases of severe sepsis. In total, patients contributed 20,000 patient days on the Hospitalist service. What is the incidence density (per 1,000 patient-days) of severe sepsis on this service? Report your answer to two decimal places (e.g., 0.25).