Every insurer shall file with the commissioner every manual of classification, rule, rate, rating plan, rating system, and modification of any of these which it proposes to use; provided, that classification rates may be modified without additional filings to produce rates for individual risks which are lower than those filed and which evaluate variations in physical or moral hazards, individual risk experience, or expense provisions, and which are not inadequate or unfairly discriminatory. Every filing shall state the proposed effective date of the plan or system and shall indicate the character and extent of the coverage contemplated. When a filing is not accompanied by the information upon which the insurer supports that filing, and the commissioner does not have sufficient information to determine whether the filing meets the requirements of the chapter, the commissioner may require the insurer to furnish the information upon which it supports the filing. The information furnished in support of a filing may include: (1) the experience or judgment of the insurer or rating organization making the filing, (2) its interpretation of any statistical data it relies upon, (3) the experience of other insurers or rating organizations, or (4) any other relevant factors. A filing and any supporting information shall be open to public inspection.