Every return made to the commissioner by any person required to make returns of the value of its properties or franchises to the commissioner under this article or Article 9 or Article 12 of this chapter and every document used to arrive at evaluation within the custody of the commissioner or the department, with the exception of income tax returns, shall be made available for inspection upon the request of any interested person at a reasonable time and accessible place to be reasonably determined by the commissioner. It is the intent of this Code section to make the returns and documents easily and readily available for public inspection, and the discretion of the commissioner shall be exercised accordingly.