(1) The commissioner shall promulgate reasonable rules and statistical plans, reasonably adapted to each of the rating systems on file with him or her, which may be modified from time to time and which shall be used thereafter by each insurer in the recording and reporting of its loss and countrywide expense experience, in order that the experience of all insurers may be made available at least annually in such form and detail as may be necessary to aid him or her in determining whether rating systems comply with the standards set forth in RCW 48.19.020 and 48.19.030. Such rules and plans may also provide for the recording and reporting of expense experience items which are specially applicable to this state and are not susceptible of determination by a prorating of countrywide expense experience.

(2) In promulgating such rules and plans, the commissioner shall give due consideration to the rating systems on file with him or her and, in order that such rules and plans may be as uniform as is practicable among the several states, to the rules and to the form of the plans used for such rating systems in other states.

(3) No insurer shall be required to record or report its loss experience on a classification basis that is inconsistent with the rating system filed by it.

(4) The commissioner may designate one or more rating organizations or other agencies to assist him or her in gathering such experience and making compilations thereof, and such compilations shall be made available, subject to reasonable rules promulgated by the commissioner, to insurers and rating organizations.

(5) Reasonable rules and plans may be promulgated by the commissioner for the interchange of data necessary for the application of rating plans.