An insurer shall maintain a complete record of all complaints it has received during the next preceding three (3) years, or since date of last examination by the superintendent or other similar supervisory authority, whichever period is shorter. The record shall show the total number of complaints, classification by line of coverage, nature of each complaint, disposition of the complaint and time it took to process each complaint. For purposes of this section “complaint” means any written communication primarily expressing a grievance.