For all health insurance policies the insurer shall maintain reserves which place a sound value on its liabilities under such policies and which are not less than the reserves according to appropriate standards set forth in rules issued by the Director of the Department of Consumer and Business Services. Except for policies of credit health insurance, such reserves for nondisabled lives shall not be less in the aggregate than the pro rata gross unearned premiums for such policies calculated in accordance with ORS § 733.060. [1967 c.359 § 215; 1971 c.231 § 18]