191—5.41 (508) Tax on gross premiums—life companies. In determining the gross amount of premiums to be taxed hereunder, there shall be excluded:
	  1. 	 All premiums returned to policyholders or annuitants during the preceding calendar year, except cash surrender values.
	  2. 	 All dividends that, during said year, have been paid in cash or applied in reduction of premiums or left to accumulate to the credit of policyholders or annuitants.