Amounts chargeable to and available from Federal sources for inpatient and outpatient services provided through Saint Elizabeths Hospital as authorized by 24 U.S.C. 191, 196, 211, 212, 222, 253,1

and 324; 31 U.S.C. 1535; and 42 U.S.C. 249 and 251 shall not exceed the estimated total cost of such services as computed using only the proportionate amount of the direct Federal subsidy appropriated under this heading.