You could somehow come up with a "standard accepted income" for given professions (these are totally from the arse, of course, but the idea holds) like CEO, 1 million, surgeon, 500k, general practitioner, 250k, nurse 60k, whatever. How you come to those numbers is left to the reader. You'd also generate 'baseline' for other expenses.
Then you compare given hospitals to those numbers and where they exceed them, that is counted as "income" - if they're paying the CEO 2m vs the 1m expected, that's 1m of income.
Then you compare given hospitals to those numbers and where they exceed them, that is counted as "income" - if they're paying the CEO 2m vs the 1m expected, that's 1m of income.