There is hereby created the “Oklahoma Housing Trust Fund” to be administered by the Oklahoma Housing Finance Agency. The fund shall be a continuing fund, not subject to fiscal year limitations, and may consist of private monies and federal and state funds. A minimum of sixty-five percent (65%), but not to exceed seventy-five percent (75%) of all annual expenditures from the Oklahoma Housing Trust Fund shall be made for the purpose of providing affordable housing in counties with a population of less than four hundred ninety thousand (490,000) according to the latest federal decennial census.