Each county superintendent of schools shall annually, at such time as is required by the Superintendent of Public Instruction but not later than July 15th, submit to the Superintendent of Public Instruction a complete report of the attendance credited to the public schools of the county for the school year closing June 30th immediately preceding July 15th. Forms for the reports shall be furnished by the Superintendent of Public Instruction. Reports shall contain and be accompanied by such other information and reports relating to the computation of state apportionments as may be required by the Superintendent of Public Instruction.