(1) At any time prior or subsequent to April 15 of each year, the assessor may request any person known or believed to own taxable property located in his county to furnish such information or to make available for examination such records as may be required by him to determine the actual value of such property.(2) Within ten days after the execution of a mineral lease, a lessor shall file with the assessor an affidavit stating the annual net rental payable under such lease for the purposes of determining the actual value of such mineral interest where the income approach to appraisal is utilized by the assessor. Such affidavit shall constitute a private document and shall be available on a confidential basis as provided in section 39-5-120.L. 64: R&RE, pp. 315, 702, §§ 294, 1. C.R.S. 1963: § 137-5-15. L. 75: Entire section amended, p. 226, § 87, effective July 16. L. 79: Entire section amended, p. 1416, § 2, effective June 21. L. 81: Entire section amended, p. 1832, § 6, effective June 12. L. 85: Entire section amended, p. 1213, § 11, effective May 9.